aaa: search by user and groups name when added via rest-api

Topic: AAA
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1120720
Change-Id: I76c5d7647d8dff5c9f2f67e42e094e883ac2164b
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>