Configure gerritbot to be on openstack-state-management.

Put gerritbot on openstack-state-management channel and have
it report about taskflow patches and changes being submitted.

Change-Id: I2028e0cf61d1a1e805b0997d662941687d0b4277
Reviewed-on: https://review.openstack.org/31837
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins