Added ActiveRecord Relation specs - minimal code changes

@twinge - the commented out specs are failing. IMO, I think it would be best to merge this in then have you code review the individual changes I suggest to resolve failing specs. This keeps the code changes small and contextualized so I don't introduce flawed solutions into the codebase.

That's my vote, but I'm happy to change the format of resulting PRs to maximize efficiency and minimize amount of your time spent on this.