aaa: Add support to principal field in ui,rest-api, and built-in extension

Change-Id: I5ba5d75449afd1ecdf75e7b335b4ab5cb32d10ce
Bug-Url: https://bugzilla.redhat.com/1120720
Toppic: AAA
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>