Problem: zproc hangs when reading from stdin socket
Problem: zproc hangs when reading from stdin socket

Solution: ZeroMQ sockets blocks by default, do not try to read
from it all the time, only one. Add unit test case to test it.

opedroso/czmq,zeromq/czmq,zeromq/czmq,opedroso/czmq,zeromq/czmq,zeromq/czmq,zeromq/czmq,opedroso/czmq,opedroso/czmq,zeromq/czmq,zeromq/czmq,opedroso/czmq,opedroso/czmq,opedroso/czmq,zeromq/czmq,opedroso/czmq,opedroso/czmq