SAK-25926 Add option to allow users to see group membership in site info


git-svn-id: https://source.sakaiproject.org/svn/kernel@307399 66ffb92e-73f9-0310-93c1-f5514f145a0a
SAK-25947 Add Option to unjoin from a joinable group


git-svn-id: https://source.sakaiproject.org/svn/kernel@307443 66ffb92e-73f9-0310-93c1-f5514f145a0a