Merge pull request #13 from marcioAlmada/master

Add minimum HHVM version constraint as a platform package requirement

Author: shabbyrobe

composer.json

@@ -15,7 +15,8 @@
         }
     ],
     "require": {
-        "php": ">=5.3.0"
+        "php": ">=5.3.0",
+        "hhvm": ">=3.3.0"
     },
     "require-dev": {
         "phpunit/phpunit": "4.1.*"