Update to phpunit 4

composer.json

@@ -17,7 +17,7 @@
         "psr/log": "~1.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~3.7.0",
+        "phpunit/phpunit": "~4.0",
         "graylog2/gelf-php": "~1.0",
         "raven/raven": "~0.5",
         "ruflin/elastica": "0.90.*",