Make the bundle working with Symfony 2.2

This pull request fixes a few issues that occur when using the original bundle with Symfony 2.2. In particular it stops adding unnecessary _locale parameter to URLs (see [failed tests on travis-ci](https://travis-ci.org/schmittjoh/JMSI18nRoutingBundle/jobs/3229075)). The changes make the bundle uncompatible with Symfony 2.0 and Symfony 2.1, so it's probably better to merge them into a separate branch or reimplement the fixes in a better way.