Use study status properly

This blocks the attachment of raw data to the study until after the study metadata is approved. It also adds two buttons for admins to approve a study and to make a study public.

This finishes #476 
these `elif`s don't seem to logically group, do they need to be in the same `if/elif` or should they be made separate? In other words, are there situations where the `make_public` should be evaluated, and additionally, the `approve_study` branch should as well? I'm having a very difficult time understanding what this method as a whole does, which is making it difficult to review.