Allow group coordinators to add users to groups

[lmb244]

Users are seeing this as a barrier to entry. Group coordinators want the ability to add members to the group. Members that are added to the group, should be able to remove themselves.

• Notes: At one point, I belive this functionality was present before the .9 release. I am not sure if the code is just commented out. I am also not sure the reason behind why the decision was made to remove the functionality.