[GATE-3] Lots of reworking to handle nickname and group syncing.  JML (MSN) doesn't support removing buddies yet.. (sigh)  OSCAR has a null exception error that's occuring when I add a new buddy that I need to track down.

git-svn-id: http://svn.igniterealtime.org/svn/repos/wildfire/trunk/src/plugins/gateway@5236 b35dd754-fafc-0310-a699-88a17e54d16e