update travis

.travis.yml

@@ -1,13 +1,17 @@
 language: php
 
 php:
-  - 5.4
-  - 5.5
-  - 5.6
+  - 7.0
+  - 7.1
+  - 7.2
 
-before_script:
-  - curl -s http://getcomposer.org/installer | php
-  - php composer.phar install --dev
+matrix:
+    allow_failures:
+        - php: 7.2
 
-script: phpunit
+before_script:
+  - composer self-update
+  - composer install --no-interaction
 
+script: 
+  - vendor/bin/phpunit