moved generator bundle from require to require-dev in composer deps

Author: fabpot

composer.json

@@ -17,9 +17,11 @@
         "symfony/monolog-bundle": "~2.4",
         "sensio/distribution-bundle": "~2.3",
         "sensio/framework-extra-bundle": "~3.0",
-        "sensio/generator-bundle": "~2.3",
         "incenteev/composer-parameter-handler": "~2.0"
     },
+    "require-dev": {
+        "sensio/generator-bundle": "~2.3"
+    },
     "scripts": {
         "post-install-cmd": [
             "Incenteev\\ParameterHandler\\ScriptHandler::buildParameters",