fix dependencies on HttpFoundation component

The closeOutputBuffers() method was added to the Response class of
the HttpFoundation in Symfony 2.5. Therefore, parts that are calling
this method must depend on symfony/http-foundation 2.5 or higher.

Author: xabbuh

composer.json

@@ -18,6 +18,7 @@
     "require": {
         "php": ">=5.3.3",
         "symfony/twig-bridge": "~2.5",
+        "symfony/http-foundation": "~2.5",
         "symfony/http-kernel": "~2.1"
     },
     "require-dev": {