This is the final change required for Django 2.0 support. Instead of using
MIDDLEWARE_CLASSES use MIDDLEWARE setting. Support for new style middleware was
provided in version 0.3.0, so depend on that version. Django built-in middleware
already supports new style and plinth middleware will now support new style.
The actual semantics of the middleware don't need changes. See:
https://docs.djangoproject.com/en/2.0/topics/http/middleware/#upgrading-pre-django-1-10-style-middleware
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>