This change adds a new "type" field to users which can be one of "student",

"mentor", or "instructor". Mentors are still the superusers of the system,

and instructors are a limited class where they can see all the other users

within their own groups but cannot see anyone else, and cannot make changes.

Set myself to be an instructor and joined one of our active groups. Saw

  everything that I expected to.
Set myself to be a student and saw the limited student view.