Title: #206: IFP: Fix of names in GetUserGroups method
I do not plan to do full review but I wonder why we need `sss_get_domain_by_name` just in
ifp responder. How is this situation solved in nss responder?
Probably question to @pbrezina :-) because @celestian probably do not have a time to
update patch (if needed)
See the full comment at https://github.com/SSSD/sssd/pull/206#issuecomment-293594149