Add support for manpages.

Change-Id: I7fc77c48b515437d40f4046324cbff2536296c20
Reviewed-on: https://review.openstack.org/26284
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins