Better error messages when importing orders (api)
Set up attributes for successful order import
Fix conflict after gem money 6.0.0 release

This would bring #2737 back but we need to be able to bundle and
activemerchant current release require money < 6.0.0
Discard line items :sku key when importing orders (api)

Users might need to pass a sku in order to find a variant, some import
scripts might pass both variant_id and sku, so before before saving we
have to exclude the attributes that dont belong to a LineItem
Generate unique indexes for new styles attachments form

Fixes #3940
Ensure api/orders return updated_at with miliseconds
Remove defunkt validation
Spree.user_class class variable accepts a symbol value

Fixes #3930
refactor some checkout module methods

Fixes #3943
Add mail method translations
Scope translations for security settings + auth settings for mail methods

Fixes #3951
Only validate the month/year for CC info if there is no payment profile
A payment profile can either be a customer id or a payment profile id
Only show last digits on payment form if they exist
Added gateway_customer_profile_id and gateway_payment_profile_id to permitted attributes (for Stripe.js support)
Introduce channel attr to Order model

Could be set when importing orders from other storefronts

Conflicts:
	api/CHANGELOG.md
	api/spec/controllers/spree/api/orders_controller_spec.rb
	core/CHANGELOG.md