Add spree namespace to all translation keys
Make sure the backend gem gets built
Bump paperclip to 3.4.1

Fixes #2963
Latest Paperclip requires that attachment styles has symbolized keys
Bump httparty dependency to 0.11
Bump rabl and versioncake to latest versions
Bump acts_as_list, ffaker, json and stringex to latest versions
fixes order hook logic to run hooks when finalizing order

Fixes #2986
Add expected and actual as required CONTIRBUTING.md steps
Shipments.js needs to use Spree.url to ensure api token is passed. [Fix #2989]

fixes #2990
Remove duplicate stringex dependency from backend
[backend] Symbolize image attachment style keys before running images_spec
Extract taxonomy jstree menu to a new file

Fixes #2953
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