Fix OptionValue#for_product scope

The scope was selecting only option values of deleted variants
Revert "Order options by variant position"

Revert since OptionValue#for_product scope is fixed.  Will use a
ruby sort instead to sort values by variant position

This reverts commit 7a05f0a7a10f62944885da1ba1710d7f4d43c588.

Conflicts:
	app/models/spree/product_decorator.rb