Add scoping when matching to orders tax_zone to find possible relevant zones

Ensure default tax zone

Add cached_kind attribute to Zone

Conflicts:
	core/app/models/spree/zone.rb

Add associations to countries and states through zones - pluck ID's to optimize expensive Spree::Zone#contains? method

Conflicts:
	core/app/models/spree/zone.rb

Fix removing default tax from orders outside the default tax zone issue
Set up a Zone#kind in the db instead