Support phpunit 4.0

Still compatible with 3.7
Tests not affected

Author: clue

composer.json

@@ -12,6 +12,6 @@
         "php": ">=5.3.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "3.7.*"
+        "phpunit/phpunit": "3.7.* | ~4.0"
     }
 }