Order state changes are now tracked after all transitions, exactly like shipments and payment state transitions

Fixes #3850
Allow coupon codes to be added from admin adjustments index.

Fixes #3859
Fix AdjustmentsHelper#display_line_item showing empty brackets if a variant had no options text
Fix pluralization issues with translations + views for CreateItemAdjustments action
Add translation for FreeShipping promotion action
Remove Promomtion#order_activatable in favour of the class method of the same name
checkout/registration view should live in auth component, not frontend
Bump activemerchant to 1.40.0

Likely fix for spree/spree_gateway#105
Fixed jquery.payment formatting not applying to more than one set of gateway fields on the payments page

Conflicts:
	frontend/app/assets/javascripts/store/checkout.js.coffee
[frontend] only draw index + show routes for products
[frontend] Remove orders/destroy route
Remove UserBanners which don't appear to be used anymore

Conflicts:
	backend/config/routes.rb
Add missing 'New Country' translation
[OrderUpdater] Update totals before updating payment state so that payment_state is correctly set
The reverse tax calculation was wrong when more than one tax applied to a given product