Nobrainer, ORM for RethinkDB, support

The tests for the nobrainer.gemfile fails on Travis due to active_support not being loaded by the ORM, I think. 

Wasn't sure how to add this in with out dirtying up the tests anymore than I already have.
testing if the current ORM == NoBrainer is safer. Suppose that Mongoid one day implements `preload` to do something else, it's game over.