Improve bill address error message

"(Street + House number)" instead of "address1"
and "postcode" instead of "zipcode"

config/locales/en.yml

@@ -36,6 +36,8 @@ en:
         lastname: "Last name"
         zipcode: "Shipping address postcode"
       spree/order/bill_address:
+        address1: "Bill address (Street + House number)"
+        zipcode: "Bill address postcode"
         phone: Customer phone
       spree/user:
         password: "Password"

spec/models/spree/order_spec.rb

@@ -14,6 +14,12 @@ describe Spree::Order do
       order.save
       expect(order.errors.full_messages).to include "Shipping address line 1 can't be blank"
     end
+
+    it "provides friendly error messages for bill address" do
+      order.bill_address = Spree::Address.new
+      order.save
+      expect(order.errors.full_messages).to include "Bill address (Street + House number) can't be blank"
+    end
   end
 
   context "#products" do

spec/system/consumer/split_checkout_spec.rb

@@ -211,7 +211,7 @@ describe "As a consumer, I want to checkout my order" do
           end
 
           it "should display error message in the right order" do
-            expect(page).to have_content "Customer E-Mail can't be blank, Customer E-Mail is invalid, Customer phone can't be blank, Bill address firstname can't be blank, Bill address lastname can't be blank, Bill address address1 can't be blank, Bill address city can't be blank, Bill address zipcode can't be blank, and Shipping method Select a shipping method"
+            expect(page).to have_content "Customer E-Mail can't be blank, Customer E-Mail is invalid, Customer phone can't be blank, Bill address firstname can't be blank, Bill address lastname can't be blank, Bill address (Street + House number) can't be blank, Bill address city can't be blank, Bill address postcode can't be blank, and Shipping method Select a shipping method"
           end
         end
       end