Invalid parameter name on interface

[Steve Martinelli]

Invalid parameter name on interface

There are several classes that inherit from the abstract method
AuthMethodHandler.authenticate. In some cases those classes are
not using matching parameter names.

This patch changes all classes such that the signatures match.
Prior to this there were four different signatures:

authenticate(self, context, auth_payload, auth_context)
authenticate(self, request, auth_info, auth_context)
authenticate(self, request, auth_payload, auth_context)
authenticate(self, request, auth_payload, user_context)

The new common signature should be:

authenticate(self, request, auth_payload, auth_context)