Broadcast Communication Error to Secondary Controller

Suppose there is a primary computer wired to the system (using one or more USB connections), and a secondary computer connected to the primary computer over ZMQ. If the primary computer loses one of the USB connections (because it is unplugged or non-functional), the secondary computer has no way to no that the connection has been lost.

In a similar fashion, because a ZMQ connection fails silently, when the secondary computer fails to connect to the primary computer over the network (either because one computer isn't on the right network or because of a network error), there is no indication to the secondary operator that anything is wrong.

Either of these circumstances should post an error on the secondary computer.

Affected modules:
- system_connection
- zmq_comm