- extracted application state into separate directories
  - media
  - static-collected
  - whoosh_index
- use static-collected host-mounted volume for Django to collectstatic
and for nginx to serve /static/

This reverts commit 4b81d75d.

We suggest to run all commands through the Docker Compose CLI, in so we
have a stable reference for the way how we do things with the
containers.

Also manage.py is favoured over django-admin.py, as it is the official successor.

Note that the `-w WORKDIR` Docker Compose parameter is not supported on older Docker engines, why the
workaround with an enclosed bash command `sh -c 'cd ... && '` is being used.

This reverts commit f84a00a0.

This reverts commit f1e530a0.

This way we can use the caching of image layers more efficiently.

- mkdir -p is implicit when using WORKDIR