Makes cvv_response optional

Fixes #3330
Execute transition callbacks in promos

Fixes #3364
Fix coupon code activation

Fixes #3363
Related to #3222
Show useful error messages for promotion rules and actions

Fixes #3358
Generate sensibly lengthed SKUs

Fixes #3359
Add ability to convert Spree::CreditCard objects into ActiveMerchant::Billing::CreditCard objects

This is because some gateways, such as USA EPay, will only take a AM::Billing::CreditCard object.

See here: https://github.com/Shopify/active_merchant/blob/7451976878ee35bdb753e905ccd9a833af0d1a5d/lib/active_merchant/billing/gateways/usa_epay_advanced.rb#L1296

Conflicts:
	core/spec/models/credit_card_spec.rb
Dsplay right price when product has variants

When a user loads the product page it was not displaying the price
of the variant chosen on the form

Fixes #3379
Fixes #3383
Use Ruby 1.8 hash in core/spec/requests/products_spec.rb
Fix issue where adjustments page would not have 'continue' link in certain circumstances

Fixes #3100
Fix sample order generator to make the new orders show up as complete
Bump to Rails 3.2.14
Update rails version in README [ci skip]
enhanced order import though api. support for shipping address,
shipments, adjustments and payments
Add option_values to variant template [api]

Fixes #3460
improved exception reporting while importing orders through api
use .present? for imported order fields, to avoid empty strings
allow completed_at to be passed in new orders api
Evaluate coupon codes ignoring case

Current implementation forces case which causes confusion for users
who see their entered coupon code change after input. This strategy
allows user input to be maintained, but normalizes the code before
evaulation using a single, shared method.