Add Configurable Retry + Backoff for Increased Stability on Low Quality Networks

[1ubuntuuser]

>>>>>> wormhole >>>>>> internet >>>>>>>> wormhole >>........>> internet ...>>>>>>>> wormhole/LIA Current behaviour Wormhole gives up after a few retries when the network is down

Ideal behaviour Wormhole allows the user to configure number of server connection retries.

This feature would be particularly useful for those using wormhole for IoT devices. Currently, if the internet drops off, wormhole gives up connecting pretty quick. I've never programmed with Go so for now, I'm going to program my own health checker that will simply kill and restart the wormhole process retry the connection.