Add a custom handler for nelmio/api-doc-bundle

This handler sets input & output properties on the @ApiDoc tag through reflection
Mark main resources with resource=true
Add support for serializer groups to ApiDoc handler

Serializer groups feature implemented in d46bcfddce0de75fd88190bb4b485d1f6fc48096
Only modify apidoc tags on methods defined directly in the RadRestController

Developer added documentation might disappear when his methods are overridden from RadRestController.
This also saves instanciating of classes when unneeded.
Add tests for ApiDoc RadRestHandler
Specify covered classes on each unit test

Make sure the reported coverage comes from the tests belonging to the class,
not random other tests that call methods on the class.
Add tests for ApiDoc RadRestHandler (overridden methods & serialization)
Merge branch 'feature/specify-coverage' into develop
Merge branch 'feature/apidoc-extractor' into develop

* feature/apidoc-extractor:
  Add tests for ApiDoc RadRestHandler (overridden methods & serialization)
  Add tests for ApiDoc RadRestHandler
  Only modify apidoc tags on methods defined directly in the RadRestController
  Add support for serializer groups to ApiDoc handler
  Mark main resources with resource=true
  Add a custom handler for nelmio/api-doc-bundle