compile but don't use zmq
make zmq4 optional
make zmq4 the default
Merge pull request #91 from da2ce7/zmq4

Server - Client Backwards Incomparable Change! Move to ZMQ4.
Removes system zmq dependance, now zmq is integrated in-source.
Fix for Android version, for Pete.

Signed-off-by: FellowTraveler <F3llowTraveler@gmail.com>