hosts's username and password, if your remote host requires
authentication.
NEW FEATURE: The possibility to execute third party scripts. This should
make extending this image easier.
REFACTORING: Dockerfile now starts with run.sh instead of suprevisor.
This makes it much easier to see any errors that might creep into the
code. Also note that the script now relies on POSIX-compliant commands
only so the executor has been changed from /bin/bash to /bin/sh.