remove deps to gelf-graylog, which is a dependency of the app

composer.json

@@ -19,7 +19,6 @@
         "doctrine/doctrine-migrations-bundle": "^3.0",
         "doctrine/orm": "^2.13.0",
         "erusev/parsedown": "^1.7",
-        "graylog2/gelf-php": "^1.5",
         "knplabs/knp-menu-bundle": "^3.0",
         "knplabs/knp-time-bundle": "^1.12",
         "knpuniversity/oauth2-client-bundle": "^2.10",