Fix wrong discount calculation with flat percent promotions when there are more than one line item in the order

Fixes #3054
Add default order to the variants_including_master product association
Translation fix in StockTransfersController. Make back to transfers buttons consistent.

Fixes #3362
Remove optimistic lock from inventory units.

Fixes #3238
Fixes #3367
Show useful error messages for promotion rules and actions

Fixes #3358
Bump rspec-rails to 2.14.0

Fixes #3356
Update Font Awesome to version 3.2.1 with 361 icons total now available in admin

Fixes #3355
Remove items with quantity 0 on cart page

Read line removed in e07f4569f2dd63f411d81b6cf380140a73ac1de1 and add
spec to prove why it needs to be there for now

Fixes #3353
Generate sensibly lengthed SKUs
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

Conflicts:
	core/spec/models/credit_card_spec.rb