Turning backend into a gem; separating and re-arranging more things in
frontend

Add requires for backend and frontend to spree.rb
Remove Spree::Core::StoreHelpers, replaced with Spree::StoreHelper

Remove store_helpers
Re-create current_order object if backend currency changes

Fixes #2340
Fix Ruby 1.8 syntax incompatibility within Spree::Api::BaseController
Merge branch 'master' into split_core

* master: (33 commits)
  Fixing tiny typo
  Show the correct item total on order details page
  Adjustments can now be open/closed/finalized - Add a state machine to adjustments with states open, closed, finalized - Once an adjustment is finalized, it cannot be changed, but an   adjustment can toggle between open/closed as needed - Update Admin UI to allow users to toggle an adjustment's state
  Bump to Rails 3.2.10
  fix #2347 fluid images for product
  Must set master to be deleted as well in scopes_spec
  Move order population responsibility out of OrdersController
  [api] Fix 1.8 syntax error in countries_controller
  Remove auth-specific translations from core
  Auto-orient uploaded images based on EXIF data
  Use line_item price instead of variant price
  Make admin/orders/shipments_spec.rb not dependent on a checkbox's id
  Correct Taxon class reference in taxon.rake
  Updated paperclip rake command with proper class info for spree.
  Remove debug from -v/--version call
  Fixed issue with duplicate thumbnails on ProductController#show
  move gateway form required chars "*"
  Improves promotion#products collection method
  Fix The action 'show' could not be found for Spree::Admin::TaxSettingsController
  Fix - Shipment includes vat is allways false after save
  ...

Conflicts:
	core/lib/spree/core/calculated_adjustments.rb
	core/spree_core.gemspec
	frontend/app/controllers/spree/orders_controller.rb
	frontend/config/routes.rb
	promo/spec/models/order_spec.rb