Adapt current tax setup to work with shipment taxes

This is a temporary step...

app/models/calculator/default_tax.rb

@@ -33,6 +33,7 @@ module Calculator
 
       [
         line_items_total(order),
+        shipments_total(order),
         per_item_fees_total(order, calculator),
         per_order_fees_total(order, calculator)
       ].sum do |total|
@@ -48,6 +49,12 @@ module Calculator
       matched_line_items.sum(&:total)
     end
 
+    def shipments_total(order)
+      order.shipments.select do |shipment|
+        shipment.tax_category == rate.tax_category
+      end.sum(&:cost)
+    end
+
     # Finds relevant fees for each line_item,
     #   calculates the tax on them, and returns the total tax
     def per_item_fees_total(order, calculator)

app/models/spree/tax_rate.rb

@@ -36,8 +36,7 @@ module Spree
     end
 
     def self.adjust(order)
-      order.adjustments.tax.destroy_all
-      order.line_item_adjustments.where(originator_type: 'Spree::TaxRate').destroy_all
+      order.all_adjustments.tax.destroy_all
 
       match(order).each do |rate|
         rate.adjust(order)
@@ -63,6 +62,7 @@ module Spree
       if included_in_price
         if default_zone_or_zone_match? order
           order.line_items.each { |line_item| create_adjustment(label, line_item, line_item) }
+          order.shipments.each { |shipment| create_adjustment(label, shipment, shipment) }
         else
           amount = -1 * calculator.compute(order)
           label = Spree.t(:refund) + label