[Common] add missing dependencies

Author: xabbuh

composer.json

@@ -15,7 +15,8 @@
         "php": ">=5.3.0",
         "jms/serializer": "~0.16",
         "symfony/config": "~2.2",
-        "symfony/validator": "~2.5"
+        "symfony/validator": "~2.5",
+        "xabbuh/xapi-model": "~1.0"
     },
     "require-dev": {
         "symfony/property-access": "~2.2",