Don’t allow indexing on service model

Making people use a property is a sure way to make sure they’re spelling
the name of the property correctly, and allows us to easily swap out
properties that call through to the underlying JSON, and properties
which are implemented as methods.

app/main/views/templates.py

@@ -237,7 +237,7 @@ def choose_template_to_copy(service_id):
             'templates': [
                 template for template in
                 service_api_client.get_service_templates(service['id'])['data']
-                if template['template_type'] in current_service['permissions']
+                if current_service.has_permission(template['template_type'])
             ],
         } for service in user_api_client.get_services_for_user(current_user)],
     )