Feature: restart containers if they become 'unhealthy'

[lachiemurray]

The HEALTHCHECK instruction is a neat way of checking that an image is running as expected. However, it doesn't have built in support for restarting a container if it is identified as being un-healthy. All that happens when a health check is failed is a status flag is updated.

It would be nice if AZTK monitored the status and automatically restarted unhealthy containers