use the official spree git repo for spree_auth_devise

Fixes #2036
Check for actual option_value before trying to get presentation attr in admin/variants/_form.html.erb
Don't automatically singularize taxonomy names within shared/_taxonomies

Rather, users should be able to choose if they want singular or plural names just by naming the taxonomies

Fixes #2038
Include 'None' for blank options in shipping category and tax category fields on products form
fix wrapping opts[:ignore_types] for single variable or array

Fixes #2034
Goodbye, Spree::Core::FileUtilz
Correctly pluralize actions in return_authorizations/index view
Really remove file_utilz
Fix return_authorizations/_form from crashing

See: http://ryanbigg.com/2012/10/javascript-arrays-and-objects/
Tidy up return_authorizations/_form JS
Remove rails_3_1.rb

This file defines a method inside ActiveRecord::NamedScope which does not appear to be used anywhere
Add workaround for rails/rails#5868
Remove distinct option from ransack call in Admin::OrdersController

Fixes #2010
Raise a better error message when testing_support/common_rake can't be found

Fixes #2041
Create a preference that allows to display the variant price as full or as a difference from product price

Fixes #2045
Don't process payments if no payment is required

Fixes #2028
Refactor Spree::BaseHelper#variant_options

Fixes #2039
stub payment_required? to be true for tests that check order complete status

Fixes broken tests caused by fix for #2028
Alphabetize translations
Use JavaScript translations in image_settings.js.erb

This avoids the same problem as explained in #1915