Allow using either of PHPUnit 3.7.* or PHPUnit 4.0.*

Author: Alexander Obuhovich

composer.json

@@ -18,7 +18,7 @@
 		"behat/mink-selenium2-driver": "~1.1@dev",
 		"symfony/event-dispatcher": "~2.4",
 		"pimple/pimple": "~2.0@dev",
-		"phpunit/phpunit": "~3.7|~4.0"
+		"phpunit/phpunit": ">=3.7.8"
 	},
 
 	"require-dev": {