Remove symfony/symfony requirement

Author: wouterj

composer.json

@@ -19,7 +19,6 @@
         "symfony/framework-bundle": "~2.3"
     },
     "require-dev": {
-        "symfony/symfony": "2.6.*",
         "symfony-cmf/core-bundle": "~1.1",
         "symfony-cmf/testing": "~1.1",
         "matthiasnoback/symfony-dependency-injection-test": "0.*",