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
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)