Exclude unused URLs from core Oscar apps

ecommerce/extensions/app.py

 from oscar import app
+from oscar.core.application import Application
 
 
 class EdxShop(app.Shop):
     # URLs are only visible to users with staff permissions
     default_permissions = 'is_staff'
 
+    # Override core app instances with blank application instances to exclude their URLs.
+    promotions_app = Application()
+    catalogue_app = Application()
+    offer_app = Application()
+    search_app = Application()
+
 
 application = EdxShop()