- Fixed all the failing test cases at http://greenbytes.de/tech/tc/httpauth

  except for "simplebasicrealmsqc" and the warnings. Note that the warnings
  are not fixed to keep compatability with the old spec (RFC 2617).
- Made the authentication code standalone such that it no longer requires to
  be directly injected into http.cpp to compile.
- Added unit test coverage for the HTTP authentication code.

REVIEW: 101986