add post build workspace cleanup publisher

Change-Id: Id541aaa8173202bf141f389c7258e0dd43b39472
Reviewed-on: https://review.openstack.org/31448
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins