- Set Meta.app_label on models created in the tests
 - Use logging.NullHandler instead of django.utils.log.NullHandler
 - Use oscar.core.loading.get_model() instead of django's get_model
 - Remove template tags '{% load url from future %}'

Adds new functional tests for ShippingAddressView, PaymentDetailsView
and ThankYouView.
It's the second part of #1645.

Notes

* Adds a custom template to be able to test some functionalities of
  PaymentDetailsView
* Adds an helper to the CheckoutMixin

The config was picking the wrong directory so the custom test templates
were not used during tests.

Notes

- Fix missing i18n load tags
- Remove mixed tab/space indentation
- Add two settings tests

Allow using a different app than promotions as the homepage view.

Django 1.4 is not supported anymore, hence we can remove it.

Fixes #881

I used the existing script [1] that cooperates very nicely with vim.
1: https://github.com/rory/django-template-i18n-lint

Fixes #676

Distinguish it from the other folders which each define a category of
test.