Added a Peer.isLocal() utility method

Simplify the local peer bean check (avoids a dependecy to IDirectory)
Python XMPP directory: renamed _jid_uid to _jid_peer
Python XMPP bot: removed the custom body in __send_message()
Added a name to all POM files + XML reformat
Added Java XMPP transport based on Babbler

Babbler: https://bitbucket.org/sco0ter/babbler/overview

Not yet tested.