Delete dead code Spree::Order#price_adjustments

This method returns the same thing as the Spree::Order#line_items_adjustments scope, but in a slightly less useful format (an array instead of a relation). The method's name is also totally inaccurate, as currently the only adjustments that appear on line items are tax adjustments for inclusive tax rates, which by definition have no effect on the price whatsoever...

app/models/spree/order.rb

@@ -723,15 +723,7 @@ module Spree
     end
 
     def total_tax
-      (adjustments.to_a + price_adjustments.to_a).sum(&:included_tax)
-    end
-
-    def price_adjustments
-      adjustments = []
-
-      line_items.each { |line_item| adjustments.concat line_item.adjustments }
-
-      adjustments
+      (adjustments.to_a + line_item_adjustments.to_a).sum(&:included_tax)
     end
 
     def price_adjustment_totals

app/models/spree/tax_rate.rb

@@ -83,8 +83,8 @@ module Spree
       order.adjustments(:reload)
       order.line_items(:reload)
       # TaxRate adjustments (order.adjustments.tax)
-      #   and price adjustments (tax included on line items) consist of 100% tax
-      (order.adjustments.tax + order.price_adjustments).each do |adjustment|
+      #   and line item adjustments (tax included on line items) consist of 100% tax
+      (order.adjustments.tax + order.line_item_adjustments.reload).each do |adjustment|
         adjustment.set_absolute_included_tax! adjustment.amount
       end
     end

app/views/spree/admin/orders/_form.html.haml

@@ -4,7 +4,7 @@
 
   = render :partial => "spree/admin/orders/shipment", :collection => @order.shipments, :locals => { :order => order }
 
-  = render :partial => "spree/admin/orders/_form/adjustments", :locals => { :adjustments => @order.price_adjustments, :title => t(".line_item_adjustments")}
+  = render :partial => "spree/admin/orders/_form/adjustments", :locals => { :adjustments => @order.line_item_adjustments, :title => t(".line_item_adjustments")}
   = render :partial => "spree/admin/orders/_form/adjustments", :locals => { :adjustments => order_adjustments_for_display(@order), :title => t(".order_adjustments")}
 
   - if order.line_items.exists?

spec/models/spree/adjustment_spec.rb

@@ -221,7 +221,7 @@ module Spree
         end
 
         it "does not crash when order data has been updated previously" do
-          order.price_adjustments.first.destroy
+          order.line_item_adjustments.first.destroy
           tax_rate.adjust(order)
         end
       end