Create Dockerfile for Kronos

Docker has 3 kronos services, one for all, one for readonly, one for collector. When docker is run, all three are started. Three ports are mapped. The log directory is mapped to `/var/log/kronos`. Settings file at `/etc/kronos/settings.py` is mapped into the docker.
@marcua /var/log/kronos:/var/log doesn't work.

Also, I thought we were using 1 docker per instance, so what is the problem with /etc/kronos:/etc/kronos?