[ResourceBundle]  added the ability to configure services, forms, twig extensions, validations and mapping using yml or xml files (or both)
[CoreBundle] Fixed problem when this bundle is configured to load YAML files.
[ResourceBundle] Fixed some duplicate code and incorrect exception namespace
Merge pull request #2092 from gperdomor/issue_2091-YML-ConfigFiles

[ResourceBundle]  added the ability to configure services, forms, twig extensions, validations and mapping using yml or xml files (or both)