backporting all changes from cvs version done by quicksketch; adding buddylistinvite module to 4-7 branch

Until someone takes the time to update the buddylist_access module to 4-7, I'm removing it. It seems too close in functionality to og.module to be worth my time.

fix access when no groups are chosen. also add a UI for enabling/disabling the access control in this module. this is a required step. see the admin/settings/buddylist_access page