packaging: setup: print proper message suggesting to run as root

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1037451
Change-Id: I3850b5c474e7bae47f2b240c19dee690d6c9e3ef
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>