investigate pm2-runtime mode for Docker

[hjwilli]

PM2 is being used to keep process alive in the lab (the main server and ai processes) and machine (the main server process) docker container instances.

PM2 has a pm2-runtime mode optimized for working in production Docker environments. Investigate and possibly switch to pm2-runtime.

Also investigate not using PM2 for machine instances as they are managing only one process, and instead use the docker restart policy.