title: zeromq: unicode not allowed, use send_unicode
body: <p>I am getting error on zeromq python while sending strings through ROUTER SOCKET. String type messages are receveid successfully but some times, a unicode message throws exception <code>"Type Error: unicode not allowed. use send_unicode".</code> Although I have been trying to use msg.encode('utf-8'). BUt I cant figure out a way to get over with it.
  I am on python 2.7.3. I am not using pyzmq (import zmq only). Looking forward to your suggesitons :) Thanks</p>
  
  <p>if backend in sockets:</p>
  
  <pre><code>        request=backend.recv_multipart()
          #print ("Backend Thread is ready")
          worker_id,client_id = request[:2]
  
          if client_id != b"READY" and len(request) &gt; 3:
              #print (len(request))
              empty2,reply  = request[2:]
              router_socket.send_multipart([client_id, reply.encode('utf-8')])
  </code></pre>