added phpunit to require dev section, update travis.yml

Author: igor-chepurnoi

.travis.yml

@@ -19,4 +19,4 @@ install:
 
 script:
   - vendor/friendsofphp/php-cs-fixer/php-cs-fixer fix --dry-run --diff
-  - phpunit
+  - vendor/bin/phpunit --verbose

composer.json

@@ -19,7 +19,8 @@
         "yiisoft/yii2": "*"
     },
     "require-dev": {
-        "friendsofphp/php-cs-fixer": "~2.0"
+        "friendsofphp/php-cs-fixer": "~2.0",
+        "phpunit/phpunit": "~6.0"
     },
     "autoload": {
         "psr-4": {