Fix bug in array merge

We were unable to mock charges with more than one refund because the merge was limited by the size of the array in the fixture.

The receiver of the `zip` method limits the size of the output.
Refactor in preparation for live Stripe testing
Updated delete customer subscription endpoint so it deletes the subscription if the at_end_period parameter is not true
Use test helpers
Require refactor
Refactor out redundancy
Strict params for Stripe::Plan.create
Added brand attribute to cards
Reformatted refunds array to hash /w data

Matches API changes made on 2014-06-17
Merge branch 'refund-data' into api-2014-06-17

* refund-data:
  Reformatted refunds array to hash /w data
Add an 'id' field to the refunds object
Merge branch 'add-id-to-refunds' of https://github.com/charitywater/stripe-ruby-mock into live-tests
More lenient strategy config
Add message when running live tests
Live test stripe refund id
Test and update helper strategy configuration
Upgrade stripe-ruby gem to 1.14.0
Throw up some docs
Fixed plan not expanding in subscription objects
New subscriptions show up before old ones