Code review by sstok

Author: Jan0707

composer.json

@@ -21,7 +21,7 @@
     ],
     "require": {
         "php": ">=5.6",
-        "symfony/symfony": "~2.8|~3.0",
+        "symfony/symfony": "~2.8|~3.0|^4.0-BETA",
         "twig/twig": ">=1.5.0",
         "doctrine/orm": "~2.4,>=2.4.5",
         "doctrine/mongodb-odm": "^1.1.5"