Naming of system groups

[Maxwell Kanat-Alexander]

> How about we rename them all, but continue to accept the legacy names of 
> current ones in UserInGroup(), using a simple mapping table?

	Yeah, I agree with that. But then this definitely needs a release note,
so that somebody doesn't say something like, "I made a group called
editusers and it does strange things!"

	And it also needs a migration script in checksetup.

	Oh, and for everybody who's customized their Bugzilla (which is pretty
much everybody), if they've used the old groupnames manually in their
own functions or schema, they will break...

	-Max