Add healthcheck endpoint to server

[emoritzx]

This will allow for readiness/liveliness probes for container orchestrators (such as docker-compose or kubernetes)

[kahst]

Good idea! Do you think the response should be consistent with other responses and have the form

data = {'msg': 'Server is healthy.'}
return json.dumps(data)

with a JSON payload?

[emoritzx]

Sounds good. Updated to match.

[kahst]

Great, thanks.