Dockerfile for Jia and some convenience tooling (don't review yet)

This Dockerfile expects a settings.py in /etc/jia/settings.py on the host machine.  I'll include some init.d or supervisord tooling to run the docker instance on the host machine once I figure that out.
Almost!  It's the other direction---copies `supervisord.conf` from the host OS (in this directory) into the container.  Supervisord allows us to run both the scheduler and Jia itself by running a single command (CMD ["/usr/bin/supervisord"]).