Add hwclient/server examples against JeroMQ 0.3.4

From the example at
http://zguide.zeromq.org/page:all#Ask-and-Ye-Shall-Receive; specifically
http://zguide.zeromq.org/java:hwclient and
http://zguide.zeromq.org/java:hwserver
Add ZmqMain for experimentation
Use 127 IP vs. of localhost for compat with jzmq
Microbenchmark ZeroMQ transport performance

See comments at #13
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Move ZmqMain (main) => ZmqExpermients (test)
Merge pull request #13 from cbeams/zmq