Add book verification for admins

Super short @houndci @georgetmayorga @cgruppioni
@jsteiner : Yes, there was a field that I put in in a past commit - it just completely slipped my mind until recently that I had it, hence this branch+PR (now more relevant that I actually have admins)

@gabebw : What's an effective way to do this? Is there a way to say 'If this particular variable changed in the params, check if it's an admin checking it'?