Update language handling for Django CMS 2.4

Django CMS >= 2.4 stops using ``cms.middleware.multilingual.MultilingualURLMiddleware``
in favor of ``django.middleware.locale.LocaleMiddleware`` so update
the middleware settings accordingly.  ``LocalMiddleWare`` also requires
identifying language-aware patterns using ``i18n_patterns``.
See http://docs.django-cms.org/en/latest/upgrade/2.4.html#removed-the-multilingualmiddleware

In order to use ``i18n_patterns`` with the storybase app URLs, include
them using ``include`` instead of importing and concatenating them to
``urlpatterns``.

Add ``cms.middleware.language.LanguageCookieMiddleware`` to middleware
See http://docs.django-cms.org/en/latest/upgrade/2.4.html#added-languagecookiemiddleware

Addresses #660
Remove simple_language_changer

This was deprecated in Django CMS 2.4

See http://docs.django-cms.org/en/latest/upgrade/2.4.html#pending-deprecations

Addresses #660
Switch to "new-style" url tag

Starting with Django 1.5, an unquoted url name like::

    {% url myview %}

won't work ("myview" is interpretted as a variable name)
and needs to be changed to::

    {% url "myview" %}

Addresses #660
Mock as_view when testing view class methods

Mock the ``as_view()`` method of a class-based view when
unit testing methods of a view class in order to properly
bind the view arguments and keyword arguments.

See http://tech.novapost.fr/django-unit-test-your-views-en.html
Use copy instead of django.utils.copycompat

``django.utils.copycompat`` will be deprecated in Django 1.6. We
don't need it for the version of Python we support. Remove it.

Addresses #660
s/django.conf.urls.defaults/django.conf.urls/

The module ``django.conf.urls.defaults`` will be deprecated in
Django 1.6.  Use ``django.conf.urls`` instead.

Addresses #660
Update use of cache_page() decorator

Update use of the ``cache_page()`` decorator to match the correct
signature.  The old way of calling it will be deprecated.

Addresses #660
Use standalone localflavor app

``django.contrib.localflavor`` will be removed from Django core
so use the standalone app instead.

Addresses #660
Properly set up view in test

The ``story_id`` keyword argument wasn't bound to the view.

Addresses #660