Sample zpub / zpush CLI tools.
More CLI example tools.

Five tools are now available :
* zpush / zpub : read lines from the standard input and respectively push / publish them to a target type
* zpull / zsub : receives messages from a target and dump them on stardard output.
* zservice : responsible to poll an input socket and replicate message to an output socket.

Two configuration service types are provided :
* pull2pub : PULL input, PUB output
* sub2push : SUBSCRIBE input, PUSH output