make tests runnable with zmq 3.2
fixed failing test
no need to run event machine in a separate thread
socket.send_string does not return a boolean
don't raise an exception when a message cannot be sent. caller needs to check return code anyway.
relax dependency on ffi-rzmq. it works fine with the latest version.
color spec output
lock down ffi-rzmq to the latest version (which properly supports zmq 3.2.2) 
don't break setsockopt abstraction
provide hwm setter for zmq 3.2.2
added a note about closing messages to avoid memory leaks
Merge pull request #21 from skaes/zmq32-fixes

Zmq32 compatibility