Minion restart if master is not responding

Adds config options so minion can ping master to ensure a connection. If the ping fails the minion has the option to restart. This solves the issue of a master that changes IP addresses (DDNS/CNAME)

/perhaps worth investigating/
 - instead of using a ping_interval, the scheduler could be updated to throw exceptions outside the thread into the main thread.

- instead of restarting the minion for a new IP address to take effect.  Perhaps could update all the sockets to use the new IP address.