Fix symfony req

composer.json

@@ -24,7 +24,7 @@
     },
     "require": {
         "php": ">=5.5",
-        "symfony/symfony": "^2.6",
+        "symfony/symfony": "^2.7",
         "doctrine/orm": "^2.3",
         "doctrine/doctrine-bundle": "^1.2",
         "twig/extensions": "^1.0",