diff --git a/.travis.yml b/.travis.yml
index 16da27f..615d802 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,7 +13,9 @@ matrix:
     - php: nightly
   fast_finish: true
 
-before_install: composer self-update
+before_install:
+  - composer self-update
+  - if [[ $TRAVIS_PHP_VERSION = 5.4 ]]; then composer update; fi;
 
 install: composer install
 
diff --git a/composer.json b/composer.json
index 7afa81f..1482d5b 100644
--- a/composer.json
+++ b/composer.json
@@ -14,12 +14,12 @@
         }
     ],
     "require": {
-        "php": ">=5.4.0",
-        "symfony/process": "^2.7"
+        "php": "^5.4 || ^7.0",
+        "symfony/process": "^2.7 || ^3.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^4.4",
-        "satooshi/php-coveralls": "dev-master"
+        "satooshi/php-coveralls": "^1.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/composer.lock b/composer.lock
index 40a87ea..68fa68b 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,36 +4,39 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "hash": "d58b143aed6a73eba11e68cf84159fd4",
-    "content-hash": "d0486d91a43295823b315860fb081ff9",
+    "hash": "ff2d8ebd5f200f6720c59914a5878786",
+    "content-hash": "87f8818a3366f964e142fbe167a56488",
     "packages": [
         {
             "name": "symfony/process",
-            "version": "v2.7.6",
+            "version": "v3.0.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/process.git",
-                "reference": "4a959dd4e19c2c5d7512689413921e0a74386ec7"
+                "reference": "dfecef47506179db2501430e732adbf3793099c8"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/process/zipball/4a959dd4e19c2c5d7512689413921e0a74386ec7",
-                "reference": "4a959dd4e19c2c5d7512689413921e0a74386ec7",
+                "url": "https://api.github.com/repos/symfony/process/zipball/dfecef47506179db2501430e732adbf3793099c8",
+                "reference": "dfecef47506179db2501430e732adbf3793099c8",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3.9"
+                "php": ">=5.5.9"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.7-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
                     "Symfony\\Component\\Process\\": ""
-                }
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -51,7 +54,7 @@
             ],
             "description": "Symfony Process Component",
             "homepage": "https://symfony.com",
-            "time": "2015-10-23 14:47:27"
+            "time": "2016-02-02 13:44:19"
         }
     ],
     "packages-dev": [
@@ -204,6 +207,177 @@
             ],
             "time": "2015-03-18 18:23:50"
         },
+        {
+            "name": "guzzlehttp/guzzle",
+            "version": "6.1.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/guzzle/guzzle.git",
+                "reference": "c6851d6e48f63b69357cbfa55bca116448140e0c"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/guzzle/guzzle/zipball/c6851d6e48f63b69357cbfa55bca116448140e0c",
+                "reference": "c6851d6e48f63b69357cbfa55bca116448140e0c",
+                "shasum": ""
+            },
+            "require": {
+                "guzzlehttp/promises": "~1.0",
+                "guzzlehttp/psr7": "~1.1",
+                "php": ">=5.5.0"
+            },
+            "require-dev": {
+                "ext-curl": "*",
+                "phpunit/phpunit": "~4.0",
+                "psr/log": "~1.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "6.1-dev"
+                }
+            },
+            "autoload": {
+                "files": [
+                    "src/functions_include.php"
+                ],
+                "psr-4": {
+                    "GuzzleHttp\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Michael Dowling",
+                    "email": "mtdowling@gmail.com",
+                    "homepage": "https://github.com/mtdowling"
+                }
+            ],
+            "description": "Guzzle is a PHP HTTP client library",
+            "homepage": "http://guzzlephp.org/",
+            "keywords": [
+                "client",
+                "curl",
+                "framework",
+                "http",
+                "http client",
+                "rest",
+                "web service"
+            ],
+            "time": "2015-11-23 00:47:50"
+        },
+        {
+            "name": "guzzlehttp/promises",
+            "version": "1.1.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/guzzle/promises.git",
+                "reference": "bb9024c526b22f3fe6ae55a561fd70653d470aa8"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/guzzle/promises/zipball/bb9024c526b22f3fe6ae55a561fd70653d470aa8",
+                "reference": "bb9024c526b22f3fe6ae55a561fd70653d470aa8",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.5.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "~4.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "GuzzleHttp\\Promise\\": "src/"
+                },
+                "files": [
+                    "src/functions_include.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Michael Dowling",
+                    "email": "mtdowling@gmail.com",
+                    "homepage": "https://github.com/mtdowling"
+                }
+            ],
+            "description": "Guzzle promises library",
+            "keywords": [
+                "promise"
+            ],
+            "time": "2016-03-08 01:15:46"
+        },
+        {
+            "name": "guzzlehttp/psr7",
+            "version": "1.2.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/guzzle/psr7.git",
+                "reference": "2e89629ff057ebb49492ba08e6995d3a6a80021b"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/guzzle/psr7/zipball/2e89629ff057ebb49492ba08e6995d3a6a80021b",
+                "reference": "2e89629ff057ebb49492ba08e6995d3a6a80021b",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.4.0",
+                "psr/http-message": "~1.0"
+            },
+            "provide": {
+                "psr/http-message-implementation": "1.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "~4.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "GuzzleHttp\\Psr7\\": "src/"
+                },
+                "files": [
+                    "src/functions_include.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Michael Dowling",
+                    "email": "mtdowling@gmail.com",
+                    "homepage": "https://github.com/mtdowling"
+                }
+            ],
+            "description": "PSR-7 message implementation",
+            "keywords": [
+                "http",
+                "message",
+                "stream",
+                "uri"
+            ],
+            "time": "2016-02-18 21:54:00"
+        },
         {
             "name": "phpdocumentor/reflection-docblock",
             "version": "2.0.4",
@@ -255,22 +429,24 @@
         },
         {
             "name": "phpspec/prophecy",
-            "version": "v1.5.0",
+            "version": "v1.6.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpspec/prophecy.git",
-                "reference": "4745ded9307786b730d7a60df5cb5a6c43cf95f7"
+                "reference": "3c91bdf81797d725b14cb62906f9a4ce44235972"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/4745ded9307786b730d7a60df5cb5a6c43cf95f7",
-                "reference": "4745ded9307786b730d7a60df5cb5a6c43cf95f7",
+                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/3c91bdf81797d725b14cb62906f9a4ce44235972",
+                "reference": "3c91bdf81797d725b14cb62906f9a4ce44235972",
                 "shasum": ""
             },
             "require": {
                 "doctrine/instantiator": "^1.0.2",
+                "php": "^5.3|^7.0",
                 "phpdocumentor/reflection-docblock": "~2.0",
-                "sebastian/comparator": "~1.1"
+                "sebastian/comparator": "~1.1",
+                "sebastian/recursion-context": "~1.0"
             },
             "require-dev": {
                 "phpspec/phpspec": "~2.0"
@@ -278,7 +454,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.4.x-dev"
+                    "dev-master": "1.5.x-dev"
                 }
             },
             "autoload": {
@@ -311,7 +487,7 @@
                 "spy",
                 "stub"
             ],
-            "time": "2015-08-13 10:07:40"
+            "time": "2016-02-15 07:46:21"
         },
         {
             "name": "phpunit/php-code-coverage",
@@ -555,16 +731,16 @@
         },
         {
             "name": "phpunit/phpunit",
-            "version": "4.8.18",
+            "version": "4.8.24",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "fa33d4ad96481b91df343d83e8c8aabed6b1dfd3"
+                "reference": "a1066c562c52900a142a0e2bbf0582994671385e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/fa33d4ad96481b91df343d83e8c8aabed6b1dfd3",
-                "reference": "fa33d4ad96481b91df343d83e8c8aabed6b1dfd3",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/a1066c562c52900a142a0e2bbf0582994671385e",
+                "reference": "a1066c562c52900a142a0e2bbf0582994671385e",
                 "shasum": ""
             },
             "require": {
@@ -623,7 +799,7 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2015-11-11 11:32:49"
+            "time": "2016-03-14 06:16:08"
         },
         {
             "name": "phpunit/phpunit-mock-objects",
@@ -681,6 +857,55 @@
             ],
             "time": "2015-10-02 06:51:40"
         },
+        {
+            "name": "psr/http-message",
+            "version": "1.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/php-fig/http-message.git",
+                "reference": "85d63699f0dbedb190bbd4b0d2b9dc707ea4c298"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/php-fig/http-message/zipball/85d63699f0dbedb190bbd4b0d2b9dc707ea4c298",
+                "reference": "85d63699f0dbedb190bbd4b0d2b9dc707ea4c298",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Psr\\Http\\Message\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "PHP-FIG",
+                    "homepage": "http://www.php-fig.org/"
+                }
+            ],
+            "description": "Common interface for HTTP messages",
+            "keywords": [
+                "http",
+                "http-message",
+                "psr",
+                "psr-7",
+                "request",
+                "response"
+            ],
+            "time": "2015-05-04 20:22:00"
+        },
         {
             "name": "psr/log",
             "version": "1.0.0",
@@ -721,56 +946,39 @@
         },
         {
             "name": "satooshi/php-coveralls",
-            "version": "dev-master",
+            "version": "v1.0.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/satooshi/php-coveralls.git",
-                "reference": "2fbf803803d179ab1082807308a67bbd5a760c70"
+                "reference": "da51d304fe8622bf9a6da39a8446e7afd432115c"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/satooshi/php-coveralls/zipball/2fbf803803d179ab1082807308a67bbd5a760c70",
-                "reference": "2fbf803803d179ab1082807308a67bbd5a760c70",
+                "url": "https://api.github.com/repos/satooshi/php-coveralls/zipball/da51d304fe8622bf9a6da39a8446e7afd432115c",
+                "reference": "da51d304fe8622bf9a6da39a8446e7afd432115c",
                 "shasum": ""
             },
             "require": {
                 "ext-json": "*",
                 "ext-simplexml": "*",
-                "guzzle/guzzle": ">=2.7",
-                "php": ">=5.3",
-                "psr/log": "1.0.0",
-                "symfony/config": ">=2.0",
-                "symfony/console": ">=2.0",
-                "symfony/stopwatch": ">=2.2",
-                "symfony/yaml": ">=2.0"
-            },
-            "require-dev": {
-                "apigen/apigen": "2.8.*@stable",
-                "pdepend/pdepend": "dev-master as 2.0.0",
-                "phpmd/phpmd": "dev-master",
-                "phpunit/php-invoker": ">=1.1.0,<1.2.0",
-                "phpunit/phpunit": "3.7.*@stable",
-                "sebastian/finder-facade": "dev-master",
-                "sebastian/phpcpd": "1.4.*@stable",
-                "squizlabs/php_codesniffer": "1.4.*@stable",
-                "theseer/fdomdocument": "dev-master"
+                "guzzle/guzzle": "^2.8|^3.0",
+                "php": ">=5.3.3",
+                "psr/log": "^1.0",
+                "symfony/config": "^2.1|^3.0",
+                "symfony/console": "^2.1|^3.0",
+                "symfony/stopwatch": "^2.0|^3.0",
+                "symfony/yaml": "^2.0|^3.0"
             },
             "suggest": {
                 "symfony/http-kernel": "Allows Symfony integration"
             },
             "bin": [
-                "composer/bin/coveralls"
+                "bin/coveralls"
             ],
             "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "0.7-dev"
-                }
-            },
             "autoload": {
-                "psr-0": {
-                    "Satooshi\\Component": "src/",
-                    "Satooshi\\Bundle": "src/"
+                "psr-4": {
+                    "Satooshi\\": "src/Satooshi/"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -792,7 +1000,7 @@
                 "github",
                 "test"
             ],
-            "time": "2014-11-11 15:35:34"
+            "time": "2016-01-20 17:35:46"
         },
         {
             "name": "sebastian/comparator",
@@ -860,28 +1068,28 @@
         },
         {
             "name": "sebastian/diff",
-            "version": "1.3.0",
+            "version": "1.4.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/diff.git",
-                "reference": "863df9687835c62aa423a22412d26fa2ebde3fd3"
+                "reference": "13edfd8706462032c2f52b4b862974dd46b71c9e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/diff/zipball/863df9687835c62aa423a22412d26fa2ebde3fd3",
-                "reference": "863df9687835c62aa423a22412d26fa2ebde3fd3",
+                "url": "https://api.github.com/repos/sebastianbergmann/diff/zipball/13edfd8706462032c2f52b4b862974dd46b71c9e",
+                "reference": "13edfd8706462032c2f52b4b862974dd46b71c9e",
                 "shasum": ""
             },
             "require": {
                 "php": ">=5.3.3"
             },
             "require-dev": {
-                "phpunit/phpunit": "~4.2"
+                "phpunit/phpunit": "~4.8"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.3-dev"
+                    "dev-master": "1.4-dev"
                 }
             },
             "autoload": {
@@ -904,24 +1112,24 @@
                 }
             ],
             "description": "Diff implementation",
-            "homepage": "http://www.github.com/sebastianbergmann/diff",
+            "homepage": "https://github.com/sebastianbergmann/diff",
             "keywords": [
                 "diff"
             ],
-            "time": "2015-02-22 15:13:53"
+            "time": "2015-12-08 07:14:41"
         },
         {
             "name": "sebastian/environment",
-            "version": "1.3.2",
+            "version": "1.3.5",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/environment.git",
-                "reference": "6324c907ce7a52478eeeaede764f48733ef5ae44"
+                "reference": "dc7a29032cf72b54f36dac15a1ca5b3a1b6029bf"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/6324c907ce7a52478eeeaede764f48733ef5ae44",
-                "reference": "6324c907ce7a52478eeeaede764f48733ef5ae44",
+                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/dc7a29032cf72b54f36dac15a1ca5b3a1b6029bf",
+                "reference": "dc7a29032cf72b54f36dac15a1ca5b3a1b6029bf",
                 "shasum": ""
             },
             "require": {
@@ -958,7 +1166,7 @@
                 "environment",
                 "hhvm"
             ],
-            "time": "2015-08-03 06:14:51"
+            "time": "2016-02-26 18:40:46"
         },
         {
             "name": "sebastian/exporter",
@@ -1079,16 +1287,16 @@
         },
         {
             "name": "sebastian/recursion-context",
-            "version": "1.0.1",
+            "version": "1.0.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/recursion-context.git",
-                "reference": "994d4a811bafe801fb06dccbee797863ba2792ba"
+                "reference": "913401df809e99e4f47b27cdd781f4a258d58791"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/recursion-context/zipball/994d4a811bafe801fb06dccbee797863ba2792ba",
-                "reference": "994d4a811bafe801fb06dccbee797863ba2792ba",
+                "url": "https://api.github.com/repos/sebastianbergmann/recursion-context/zipball/913401df809e99e4f47b27cdd781f4a258d58791",
+                "reference": "913401df809e99e4f47b27cdd781f4a258d58791",
                 "shasum": ""
             },
             "require": {
@@ -1128,7 +1336,7 @@
             ],
             "description": "Provides functionality to recursively process PHP variables",
             "homepage": "http://www.github.com/sebastianbergmann/recursion-context",
-            "time": "2015-06-21 08:04:50"
+            "time": "2015-11-11 19:50:13"
         },
         {
             "name": "sebastian/version",
@@ -1167,32 +1375,38 @@
         },
         {
             "name": "symfony/config",
-            "version": "v2.7.6",
+            "version": "v3.0.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/config.git",
-                "reference": "831f88908b51b9ce945f5e6f402931d1ac544423"
+                "reference": "79a97025f7bf4bbf8352b5df1905aa136a531066"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/config/zipball/831f88908b51b9ce945f5e6f402931d1ac544423",
-                "reference": "831f88908b51b9ce945f5e6f402931d1ac544423",
+                "url": "https://api.github.com/repos/symfony/config/zipball/79a97025f7bf4bbf8352b5df1905aa136a531066",
+                "reference": "79a97025f7bf4bbf8352b5df1905aa136a531066",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3.9",
-                "symfony/filesystem": "~2.3"
+                "php": ">=5.5.9",
+                "symfony/filesystem": "~2.8|~3.0"
+            },
+            "suggest": {
+                "symfony/yaml": "To use the yaml reference dumper"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.7-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
                     "Symfony\\Component\\Config\\": ""
-                }
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -1210,29 +1424,30 @@
             ],
             "description": "Symfony Config Component",
             "homepage": "https://symfony.com",
-            "time": "2015-10-11 09:39:48"
+            "time": "2016-02-23 15:16:06"
         },
         {
             "name": "symfony/console",
-            "version": "v2.7.6",
+            "version": "v3.0.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "5efd632294c8320ea52492db22292ff853a43766"
+                "reference": "2ed5e2706ce92313d120b8fe50d1063bcfd12e04"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/5efd632294c8320ea52492db22292ff853a43766",
-                "reference": "5efd632294c8320ea52492db22292ff853a43766",
+                "url": "https://api.github.com/repos/symfony/console/zipball/2ed5e2706ce92313d120b8fe50d1063bcfd12e04",
+                "reference": "2ed5e2706ce92313d120b8fe50d1063bcfd12e04",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3.9"
+                "php": ">=5.5.9",
+                "symfony/polyfill-mbstring": "~1.0"
             },
             "require-dev": {
                 "psr/log": "~1.0",
-                "symfony/event-dispatcher": "~2.1",
-                "symfony/process": "~2.1"
+                "symfony/event-dispatcher": "~2.8|~3.0",
+                "symfony/process": "~2.8|~3.0"
             },
             "suggest": {
                 "psr/log": "For using the console logger",
@@ -1242,13 +1457,16 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.7-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
                     "Symfony\\Component\\Console\\": ""
-                }
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -1266,20 +1484,20 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "https://symfony.com",
-            "time": "2015-10-20 14:38:46"
+            "time": "2016-02-28 16:24:34"
         },
         {
             "name": "symfony/event-dispatcher",
-            "version": "v2.7.6",
+            "version": "v2.8.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/event-dispatcher.git",
-                "reference": "87a5db5ea887763fa3a31a5471b512ff1596d9b8"
+                "reference": "78c468665c9568c3faaa9c416a7134308f2d85c3"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/event-dispatcher/zipball/87a5db5ea887763fa3a31a5471b512ff1596d9b8",
-                "reference": "87a5db5ea887763fa3a31a5471b512ff1596d9b8",
+                "url": "https://api.github.com/repos/symfony/event-dispatcher/zipball/78c468665c9568c3faaa9c416a7134308f2d85c3",
+                "reference": "78c468665c9568c3faaa9c416a7134308f2d85c3",
                 "shasum": ""
             },
             "require": {
@@ -1287,10 +1505,10 @@
             },
             "require-dev": {
                 "psr/log": "~1.0",
-                "symfony/config": "~2.0,>=2.0.5",
-                "symfony/dependency-injection": "~2.6",
-                "symfony/expression-language": "~2.6",
-                "symfony/stopwatch": "~2.3"
+                "symfony/config": "~2.0,>=2.0.5|~3.0.0",
+                "symfony/dependency-injection": "~2.6|~3.0.0",
+                "symfony/expression-language": "~2.6|~3.0.0",
+                "symfony/stopwatch": "~2.3|~3.0.0"
             },
             "suggest": {
                 "symfony/dependency-injection": "",
@@ -1299,13 +1517,16 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.7-dev"
+                    "dev-master": "2.8-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
                     "Symfony\\Component\\EventDispatcher\\": ""
-                }
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -1323,35 +1544,38 @@
             ],
             "description": "Symfony EventDispatcher Component",
             "homepage": "https://symfony.com",
-            "time": "2015-10-11 09:39:48"
+            "time": "2016-01-27 05:14:19"
         },
         {
             "name": "symfony/filesystem",
-            "version": "v2.7.6",
+            "version": "v3.0.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
-                "reference": "56fd6df73be859323ff97418d97edc1d756df6df"
+                "reference": "23ae8f9648d0a7fe94a47c8e20e5bf37c489a451"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/filesystem/zipball/56fd6df73be859323ff97418d97edc1d756df6df",
-                "reference": "56fd6df73be859323ff97418d97edc1d756df6df",
+                "url": "https://api.github.com/repos/symfony/filesystem/zipball/23ae8f9648d0a7fe94a47c8e20e5bf37c489a451",
+                "reference": "23ae8f9648d0a7fe94a47c8e20e5bf37c489a451",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3.9"
+                "php": ">=5.5.9"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.7-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
                     "Symfony\\Component\\Filesystem\\": ""
-                }
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -1369,35 +1593,97 @@
             ],
             "description": "Symfony Filesystem Component",
             "homepage": "https://symfony.com",
-            "time": "2015-10-18 20:23:18"
+            "time": "2016-02-23 15:16:06"
+        },
+        {
+            "name": "symfony/polyfill-mbstring",
+            "version": "v1.1.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/polyfill-mbstring.git",
+                "reference": "1289d16209491b584839022f29257ad859b8532d"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/1289d16209491b584839022f29257ad859b8532d",
+                "reference": "1289d16209491b584839022f29257ad859b8532d",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "suggest": {
+                "ext-mbstring": "For best performance"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.1-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Polyfill\\Mbstring\\": ""
+                },
+                "files": [
+                    "bootstrap.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony polyfill for the Mbstring extension",
+            "homepage": "https://symfony.com",
+            "keywords": [
+                "compatibility",
+                "mbstring",
+                "polyfill",
+                "portable",
+                "shim"
+            ],
+            "time": "2016-01-20 09:13:37"
         },
         {
             "name": "symfony/stopwatch",
-            "version": "v2.7.6",
+            "version": "v3.0.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/stopwatch.git",
-                "reference": "f8ab957c17e4b85a73c4df03bdf94ee597f2bd55"
+                "reference": "4a204804952ff267ace88cf499e0b4bb302a475e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/stopwatch/zipball/f8ab957c17e4b85a73c4df03bdf94ee597f2bd55",
-                "reference": "f8ab957c17e4b85a73c4df03bdf94ee597f2bd55",
+                "url": "https://api.github.com/repos/symfony/stopwatch/zipball/4a204804952ff267ace88cf499e0b4bb302a475e",
+                "reference": "4a204804952ff267ace88cf499e0b4bb302a475e",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3.9"
+                "php": ">=5.5.9"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.7-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
                     "Symfony\\Component\\Stopwatch\\": ""
-                }
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -1415,35 +1701,38 @@
             ],
             "description": "Symfony Stopwatch Component",
             "homepage": "https://symfony.com",
-            "time": "2015-10-12 12:42:24"
+            "time": "2016-01-03 15:35:16"
         },
         {
             "name": "symfony/yaml",
-            "version": "v2.7.6",
+            "version": "v3.0.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/yaml.git",
-                "reference": "eca9019c88fbe250164affd107bc8057771f3f4d"
+                "reference": "b5ba64cd67ecd6887f63868fa781ca094bd1377c"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/yaml/zipball/eca9019c88fbe250164affd107bc8057771f3f4d",
-                "reference": "eca9019c88fbe250164affd107bc8057771f3f4d",
+                "url": "https://api.github.com/repos/symfony/yaml/zipball/b5ba64cd67ecd6887f63868fa781ca094bd1377c",
+                "reference": "b5ba64cd67ecd6887f63868fa781ca094bd1377c",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3.9"
+                "php": ">=5.5.9"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.7-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
                     "Symfony\\Component\\Yaml\\": ""
-                }
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -1461,18 +1750,16 @@
             ],
             "description": "Symfony Yaml Component",
             "homepage": "https://symfony.com",
-            "time": "2015-10-11 09:39:48"
+            "time": "2016-02-23 15:16:06"
         }
     ],
     "aliases": [],
     "minimum-stability": "stable",
-    "stability-flags": {
-        "satooshi/php-coveralls": 20
-    },
+    "stability-flags": [],
     "prefer-stable": false,
     "prefer-lowest": false,
     "platform": {
-        "php": ">=5.4.0"
+        "php": "^5.4 || ^7.0"
     },
     "platform-dev": []
 }
diff --git a/tests/Process/ProcessExecutorTest.php b/tests/Process/ProcessExecutorTest.php
index fd05211..3816695 100644
--- a/tests/Process/ProcessExecutorTest.php
+++ b/tests/Process/ProcessExecutorTest.php
@@ -63,6 +63,6 @@ public function testExecute()
         $this->assertInstanceOf('Accompli\Chrono\Process\ProcessExecutionResult', $processExecutionResult);
         $this->assertSame(0, $processExecutionResult->getExitCode());
         $this->assertSame('test'.PHP_EOL, $processExecutionResult->getOutput());
-        $this->assertSame(null, $processExecutionResult->getErrorOutput());
+        $this->assertEquals('', $processExecutionResult->getErrorOutput());
     }
 }