install gearman module from puppet forge

Install gearman module in preparation for building out gearman servers

Change-Id: Ic2f5ec7e4506784dbb8a92068961c4e8a2fc775d
Reviewed-on: https://review.openstack.org/21147
Reviewed-by: Paul Belanger <paul.belanger@polybeacon.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins