Bumping dependency to phpunit to use `4.0.*`

composer.json

@@ -16,7 +16,7 @@
         "doctrine/common": "2.4.*"
     },
     "require-dev": {
-        "phpunit/phpunit": "3.7.*",
+        "phpunit/phpunit": "4.0.*",
         "symfony/console": "2.*"
     },
     "suggest": {