Specify difference for AR models/int specs & POROs

The previous opinions were very weighted towards monolithic ActiveRecord
models with contained business logic, and had no specifications for
testing POROs and other non-AR models. These should be test-driven using
mocks and stubs, and all true unit specs require only the use of mocks
and stubs.

This also reflects my opinions that Controller and View testing using
RSpec is to be discouraged, preferring acceptance tests instead.