Added ability for custom registration tags per transport [GATE-26], working on tracking down/testing [GATE-3], more work on [GATE-20].  Much more information kept/handled for yahoo and msn transports.  MSN errors should be handled a lot better, needs to be tested.

git-svn-id: http://svn.igniterealtime.org/svn/repos/wildfire/trunk/src/plugins/gateway@5260 b35dd754-fafc-0310-a699-88a17e54d16e