fix comment to refer to checkout_step?

respond_to? isn't used on master any more and refers to older code

Fixes #3923
Change input padding to allow more horizontal room for number fields

* The 10px horizontal padding causes number fields, like the
  quantity field, to not fully display the number in the space
  allowed.

Fixes #3938
Bump ransack to 1.1.0
Check line_items key exist before mapping (api)

Sometimes we might want update only an order attribute, e.g. email, and
not the line items. In that case users would get an error response so we
better check if the key exist
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