[sugar] ejabberd now easier to install: debian & ubuntu ship our patches

[Morgan Collett]

Just when I was going to build custom ejabberd packages, Jonas
Smedegaard pointed out that Debian ships the required patches for
enabling the shared roster, and they are therefore also in Ubuntu
Intrepid (due to release in 6 days).

I've written up the much simpler process of getting ejabberd up and
running at http://wiki.laptop.org/go/Installing_ejabberd/deb.

This will make it much easier to set up a school or community ejabberd
server for collaboration, for those not using the XS images.

Regards
Morgan