packaging: setup: added systemd handling to common_utils

The new implementation provides a generic wrapper for
working with both init/systemd subsystems.

Change-Id: Ia577fd9d5627aa3a0027a01c652bee69959bb854
Bug-Url: https://bugzilla.redhat.com/1011544
Signed-off-by: Alex Lourie <alourie@redhat.com>