Listen to docker events for container status change

Currently, we relies on periodic task to sync container's status between docker and DB. The periodic task run every 60 seconds which means the container's status in Zun might be outdated.

It is better to use an event-driven approach to do container status change. Zun-compute can listen to docker events [1] to capture status change of each container and do the sync accordingly.

[1] https://docs.docker.com/engine/reference/commandline/events/