Replace mocking in generated controller specs with integration tests.

This was a terrible example and should never have been here. This
replacement isn't great, but at least is not obviously bad.

Unfortunately we cannot provide default implementations of these because
we don't have sufficient information about the data model. Specs that
require this are marked pending.

I gave up on the default approach: it doesn't work at all for models
with no attributes, and is a crapshoot if they do.

@cupakromer @JonRowe @myronmarston 

Fixes #1008