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 
Since this is changing the URI from `/error/` to `/admin/error/`, can you pull upstream master and make sure that there are no other links still pointing to `/error/`?  I know of at least one other place (in error.html) that will be broken by this change.