ZMQ.Context is a singleton.
Further qualify config key name.
ChangeForwarder bridges many inproc publishers into one TPC socket.

We'll use this to allow several coprocessor instances to publish events, while simultaneously allowing listening storm components to connect to just one port per region server.
Switch to explicit setter injection in coprocessors.

Going to see if I can eliminate usage of the injectors in test.
Add onStart and onStop to BaseCoprocessor.

This allows us to test side-effects from these events while avoiding injection.
doco
Inject and start/stop a change forwarder in change coprocessor.
Extract CoprocessorFixture#inject.