Patch

1.  fix: iterfind is not available in python 2.6, use findall instead
2.  fix: gzipped http content is not handled correctly
3.  fix: pep8 comformation
4.  The authenticate process does not conform DIGEST-MD5, see http://wiki.xmpp.org/web/SASLandDIGEST-MD5.

In step 3, another challenge is sent from server rather than a success response.
we should send a blank challenge response in step 4,
and the server send back success in step 5.

See also the codes from xmpp2:
http://pydoc.net/Python/xmpp2/0.4/xmpp2.handler.sasl/