This commit is a rough port to Django 2.1, Python 3 and a Docker based local
development setup. Tests fail/error but migrations and the web frontend are
already runnable. Task queue functionality is untested and translations seem to
have trouble.
Django 1.9 deprecates passing a context directly to the render function
in template loader. This commit creates a proper template rendering
context before rendering the mails sent from the contact form.
This commit fixes all warnings created by flake8 by removing unused
imports and variable assignments. Some wrongly indented lines are now
indented correctly.
