Implement group permissions

The group permissions overlay consists of 3 separate panels:

1) Main panel

- Title is `Manage access`
- Visibility title and section (in well), showing the current visibility of the group. This shows a small visibility icon and the short explanation (similar to setpermissions). Next to that, there is a Change button that launches the Visibility panel
- Members section, listing all of the group members and their roles. The role is in a dropdown (Manager / Member). Next to the dropdown, there is also an `x` button to remove the user/group as a member. This list scrolls infinitely on the container it's in.
- At the bottom of the list, there is an `Add more` button, that opens the `Add members` panel
- Cancel and Save button. Changes are only saved when the Save button is clicked.

2) Visibility panel

- `Visibility` title
- Large visibility icons with some text underneath, the same as the creategroup widget. Allows user to change visibility.
- Has Cancel and Update button. Update button brings you back to the Main panel

3) Members panel

- `Add members` title
- `Select users and groups to add as a member` followed by a typeahead.
- Underneath the typeahead, there is a dropdown that's right aligned that allows the user to select the roles that these new people/groups will be assigned.
- Cancel and Add button.


Some preliminary design work can be found at Sakai OAE Component Delivery/13. OAE Manage World Participants/OAE_ManageWorldParticipants_v01.pdf. However, this is not entirely complete.