Remove the deprecated/obsolete auth mixins.
Both Google's OpenID service and FriendFeed are slated to shut down
before the next release of Tornado, and FacebookMixin has been
deprecated in favor of OAuth 2.0 for a long time.
Make many doc code blocks into sphinx doctests.
Fix up documentation for the class and the Sphinx reference.
Doc updates for the auth module.
Move website/sphinx/ to docs/, remove rest of appengine website dir.