Deprecate Order#shipment as split_shipments makes it less relevant
No need to pass option on spree.promo initializer

For some reason this was making the calculator.shipping_methods nil in
the spree app initializer. It prevented users from adding their own
calculators with code like:

  Rails.application.config.spree.calculators.shipping_methods << CustomUserClass

Fixes #3118
Remove nonsense js code on backend customer details

When picking up a user at the backend customer details order step that
code would empty all address fields, including the previously set
default country

This should fix the backend build.

Fixes #3129
Add nil object check for StockLocation#fill_status [Fixes #3131]
Fix product property delete url.

Fixes #3120 #3123