Implemented ANONYMOUS authentication on the ClientXMPP class.
To use it, you just need to provide a domain (e.g 'anon.example.com')
with an optional resource (e.g 'anon.example.com/resource') as the JID,
with no password. The JID class has been improved to accept
domains as fulljid.
You can test this with echo_client.py
python echo_client.py -j anon.louiz.org/ # anonymous with a resource
# defined by the server
python echo_client.py -j anon.louiz.org/resource # anonymous with given
# resource
The "normal" authentication method still works exactly like before.
