Revert "merged branch eventhorizonpl/fix_doctrine_common_dependency (PR #591)"

This reverts commit 8198f95, reversing
changes made to 23706c4.

Author: fabpot

composer.json

@@ -10,7 +10,6 @@
         "php": ">=5.3.3",
         "symfony/symfony": "2.3.*",
         "doctrine/orm": ">=2.2.3,<2.4-dev",
-        "doctrine/common": ">=2.2.3,<2.4-dev",
         "doctrine/doctrine-bundle": "1.2.*",
         "twig/extensions": "1.0.*",
         "symfony/assetic-bundle": "2.3.*",