spray/spray — pull request #541 by jrudolph (2013-09-27 15:01:15+00:00)
Title: ! routing: AuthenticationFailedRejection now directly contains challenge headers to return, fixes #539

This has two consequences:
* it's easier to implement a custom authenticators which can now
supply the challenge headers directly instead of needing a detour
through HttpAuthenticator.getChallengeHeaders
* AuthenticationFailedRejection is now serializable