Remove unused twig-extensions dependency

Author: tommygnr

composer.json

@@ -12,7 +12,6 @@
         "doctrine/orm": "~2.2,>=2.2.3,<2.5",
         "doctrine/dbal": "<2.5",
         "doctrine/doctrine-bundle": "~1.4",
-        "twig/extensions": "~1.0",
         "symfony/assetic-bundle": "~2.3",
         "symfony/swiftmailer-bundle": "~2.3",
         "symfony/monolog-bundle": "~2.4",