Decide what exactly it means to be an admin

[nwalters512]

We treat admins and course staff sometimes the same and sometimes differently throughout the queue right now. A particularly confusing situation is that admins can join the active staff of any queue, but then the buttons that show up on questions aren't always shown according to if the user is active staff, but rather if they're on the actual course staff list, which isn't true for admins. We should adopt and implement a consistent strategy w.r.t. admins.