Remove the mock model (discuss/review)

We had discussed doing this in the past.  We are no longer really maintaining the mock model.  None of our downstream dependencies ever used it, and a mimic plugin is probably the correct way to go to give people a way to hit a fake otter service.

Keeping the mock just means that every time we change something, we have to update the mock tests.  I think that so long as we maintain the interface/abstraction between the store and the rest of otter, we're ok.