added content length header to BinaryFileResponse
Merge branch '2.2' into 2.3

* 2.2:
  slovenian translations fixed
  [DependencyInjection] fixed YamlDumper did not make services private.
  [FrameworkBundle] fix routing container parameter exception message
  update CONTRIBUTORS
  added content length header to BinaryFileResponse
  [Routing] added working test case for issue #5135