[backend] don't show adjustments or total if no adjustments or line items (respectively) exist
[backend] show additional total information in order sidebar + hide steps when checkout has expressly disabled them
Remove frontend routes from backend
Add spree namespace to all translation keys
Translate everything within core
Implement I18n testing

This allows us to check for:
1) Keys used during the test which have no translations
2) Keys that aren't used during the tests at all.

Run the tests with 'CHECK_TRANSLATIONS=1 bundle exec rspec spec' and watch the
fireworks.
BigDecimal#inspect objects now look better

Thanks to @mipearson for this tip: https://gist.github.com/mipearson/5410134
Support multiple translation keys in faux-Spree.t
Move I18n testing stuff into spree/testing_support
Add translation checking to frontend
[backend] convert over spree/admin/shared/_address_form.html.erb + refactor it
Use Spree.t within frontend views
Correctly search for keys in testing_support/i18n
exit with status code 1 if translations are missing / unused
Remove defunct translation keys, etc.

* Remove everything from `config/locales/en.yml` that couldn't be found with ack commands in `missing_translations.rb`

* Add translation for country_names.US

* Additional translation tweaks
Make translations in backend controllers, helpers, and views now use Spree.t
Require correct file in i18n_spec
Fix translations across api, core and frontend
Add missing translations for mail_method_settings, quantity, stock_locations and stock_movements
Namespace dash translations