Amend demo site to have a custom checkout app

It only creates a payment event at the moment but it will do more.  Oh
yes.

sites/demo/apps/app.py

+from oscar.app import Shop
+
+from apps.checkout.app import application as checkout_app
+
+
+class Application(Shop):
+    # Use local checkout app so we can mess with the view classes
+    checkout_app = checkout_app
+
+
+application = Application()

sites/demo/apps/checkout/app.py

+from oscar.apps.checkout import app
+
+from apps.checkout import views
+
+
+class CheckoutApplication(app.CheckoutApplication):
+    # Replace the payment details view with our own
+    payment_details_view = views.PaymentDetailsView
+
+
+application = CheckoutApplication()

sites/demo/apps/checkout/views.py

+from oscar.apps.checkout import views
+
+
+class PaymentDetailsView(views.PaymentDetailsView):
+
+    def handle_payment(self, order_number, total_incl_tax, **kwargs):
+        # Create a payment event
+        self.add_payment_event('Authorize', total_incl_tax)

sites/demo/urls.py

-from django.conf.urls.defaults import *
+from django.conf.urls.defaults import patterns, url, include
 from django.conf import settings
 from django.contrib import admin
 from django.contrib.staticfiles.urls import staticfiles_urlpatterns
 from django.conf.urls.static import static
 from django.views.generic import TemplateView
 
-from oscar.app import shop
+from apps.app import application
+
+# These need to be imported into this namespace
 from oscar.views import handler500, handler404
 
 admin.autodiscover()
 
 urlpatterns = patterns('',
     (r'^admin/', include(admin.site.urls)),
-    (r'', include(shop.urls)),
+    (r'', include(application.urls)),
 )
 
 if settings.DEBUG: