docker: if container was launched with a tty start bash otherwise loop forever to keep the container going
docker: do ADD container/docker later on so that the Dockerfile can be updated and still reuse a cached image after the major setup steps are done
docker: add some example run commands for debugging a container or having it take over host ports
docker: cleanup comments and make the installation of sshd quieter
docker: disable the ufw firewall because it is not supported in a docker container and produces a lot of error output (by reverting a510e08f9e3b2714019dc7832b1bd7b7eae4ba6c and setting an environment variable)