doctrine/doctrine2 — pull request #957 by thealjey (2014-02-20 09:41:28+00:00)
Title: makes doctrine less dependent upon the symfony yamp component

This is the last place in the framework where the class is just too tightly coupled with the symfony yaml component, that the yaml parser alone cannot be overridden without overriding an entire class.
I simply brought it in accordance with "Doctrine\ORM\Mapping\Driver\YamlDriver" where a separate method called loadMappingFile exists to parse the mapping file.