added openstack-swift config for gerritbot

Change-Id: I8febbad80d348481b25c13b44b27259d88224d40
Reviewed-on: https://review.openstack.org/29872
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins