Added "composer test" script (#699)

Author: Nyholm

.travis.yml

@@ -7,5 +7,5 @@ install:
   - composer update --prefer-stable --prefer-dist
 
 script:
-    - ./vendor/bin/phpunit
+    - composer test
 

composer.json

@@ -29,6 +29,9 @@
             "/Tests/"
         ]
     },
+    "scripts": {
+        "test": "vendor/bin/phpunit"
+    },
     "minimum-stability": "dev",
     "extra": {
         "branch-alias": {