Disconnect behavior and status endpoint

[nampereira]

Disconnect behavior
We should have the library implement a couple of disconnect behaviors: (1) retry on disconnect; (2) exit on disconnect.

A reasonable default could be to retry and check an env variable to change the behavior to exit ?

Status endpoint
Somewhat related is sending a report status on some standard topic (e.g. scene_topic/p/<program-id>/status). Essentially just reporting if the program is alive and some status/data that could be useful for debugging (list of users/objects, ...) ?

These could be periodic or triggered by a message on the topic.

[EdwardLu2018]

Added a way to reconnect in f8e5a7e, but need to add an option to disable reconnects and add status endpoint.