Modify Stackforge Libra project permissions.

Add permissions to create new branches and tags and to WIP.

Change-Id: Id53d6649a17e99f8a77da5f51003d135ca3492a3
Reviewed-on: https://review.openstack.org/21693
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Tested-by: Jenkins