Support multiple challenges for HTTP authentication.

This fixes the problem reported in the bug, but we still need
to give attention to the digest scheme. Currently we can't do
Basic auth if the HTTP response contains both a Digest challenge
and a Basic challenge!

Bug: http://code.google.com/p/android/issues/detail?id=19081
Change-Id: Ifffb307678c2afa0db1d50c1ef5fc49ec7769306
7 files changed