Add FactoryGirl stubs to RSpec
spec_helper: $LOAD_PATH project root; requires

Move `rspec` and `rack/test` to the helper: common to
all specs.

Add project root to `$LOAD_PATH` so that we can do
simple `require`s.
Add deck_spec for driving card_routes "controller"
Refactor post '/deck/:deck_id/card' route

Refactorings Applied
====================

* Inline temp variable
* Move method
Remove card_routes: all Card operations are on Decks

As implemented a card only has meaning insofar as
it has_many Decks.  While this setup now strikes
me as (possibly) wrong (doesn't a Deck have many
cards?  Or is it the case that a Card is to be
shared across Decks?  The implementation isn't
entirely clear to me)

Whatever the case, it's confusing to find deck
based methods on something called card_routes.
thus we relocate and terminate.
Add spec for add_to_deck!
Migrate Deck spec from Card Spec

Doesn't make sense for Deck model concerns to be
in a spec for Card.
Add quiz_spec for refactor of '/deck/:id/quiz/:num'
Refactor:  Push logic on to Deck
Refactor: extract get_score_for_user, initalize_session_score
Refactor: Move correctness validation to Card
Refactor:  Complete
Refactor: Use better names: num -> next_card_id