Dockerfile for Jia and some convenience tooling

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.
In `settings.py` the scheduler can be disabled. What are your thoughts on
```
[program:scheduler]
command=python /chronology/jia/runscheduler.py --config /etc/jia/settings.py
autostart=false
```
and conditionally executing `/usr/bin/supervisorctl start scheduler`? The simpler solution is to put in a single `if jia.config['PRECOMPUTE']` check in `views.py` before making any scheduler calls. Then the scheduler will always run but at least it won't be reachable.

I thought that the `PRECOMPUTE` setting currently only toggles the display of the UI control, but after reviewing it just now, I don't think it actually does anything at all. :disappointed: So I need to fix that anyway.