Fix the cookie domain used for google analytics

* A change needed to make the google analytics integration compatible
  with the universal analytics engine. Should also work for the
  traditional code.

fixes #5565
Fix validation to skip performing a query if the field is blank
fixes #5565

Conflicts:
	core/app/models/spree/product.rb
Only reload shipment items on item adjustment

The original issue fixed by
https://github.com/spree/spree/commit/a4b209c7288198124a735d99203102d86be6a935
only affected shipment calculations. Removing the reload for LineItems
allows them, and more important their descendants to be eager loaded.

fixes #5566