remove unused code

part of #843
I thought that first too. But it has side-effects leading to failing tests when removed:

```
1) FOS\RestBundle\Tests\Routing\Loader\RestYamlCollectionLoaderTest::testUsersFixture
Symfony\Component\Config\Exception\FileLoaderLoadException: Cannot load resource "FOS\RestBundle\Tests\Fixtures\Controller\UsersController".
```

and some more failures like that.