Use simplejson for message dumps

Author: worepix

cpgw/app.py

@@ -6,6 +6,7 @@
 
 import click
 import click_log
+import simplejson as json
 import zmq
 
 from cpgw.config import load_config
@@ -52,7 +53,7 @@ def on_recv(payload):
         payload['gw'] = gateway_serial
 
         payload = json.dumps(payload, use_decimal=True)
-        socket.send(payload)
+        socket.send_string(payload)
 
     gw.on_recv = on_recv