This updates all services to how zuul-scheduler works, we close the
command_socket at the last possible moment. This also means we can now
use the command socket on the filesystem as an idicator that zuul
properly shutdown.
Change-Id: I5fe1bc96c87e1177a2b94d73a9cbe505a7807202
Signed-off-by: Paul Belanger <pabelanger@redhat.com>