Automatic discovery of controller

[ygina]

The sensor SDK currently hardcodes the IP address and port of the controller. The sensor should be able to dynamically identify the controller location i.e. for generic sensor code to be compatible with different deployments. Options include using mDNS or some other local service discovery protocol.

Hosts also currently hardcode the IP address and port of the controller, though the user can configure these values as arguments to the host binary.