Set Bugzilla cookies after logging in.

Raise 401 error when trying to get user from Bugzilla but not logged in.
Added missed XMLRPC transport classes.
Bugzilla-specific transport.
In API calls to user, always cache a search from Bugzilla.
Move Bugzilla xmlrpc files around.
Always check with Bugzilla before getting/creating a user.
Added note clarifying permission to use cookie transport.