Before the images were only pulled once and then never updated which
lead to really outdated images and OS dependencies. Now all images
(including the base image for the diaspora container) are pulled when
running `setup`. So the idea is to run the `setup` command from time to
time to bring everything up to date again.
As the docker-compose.yml contains variables, it can't just be used with
docker-compose directly. So this manually use docker-compose commands
with all the required environment variables set.
