Fix issue where shipping calculators were being passed objects other than Spree::Stock::Package

Fixes #3381
Fix sample order generator to make the new orders show up as complete
Removes default_per_page method which does not work to upgrade Kaminari.
[sample] Move line items creation into orders.rb, ensuring that orders have shipments created before they transition into complete

Conflicts:
	sample/db/samples/orders.rb
Set table name using self.table_name = in Product spec
[Core] Fix mock and stub deprecations.

Also fix some Spree deprecation warnings to do with order.shipment