Fix bug in router with python2

- This code seems to have been added awhile ago, but never really
  tested in python 2. We shouldn't convert strings to unicode in
  python 2 when receiving messages. This causes a TypeError when
  forwarding messages:
  ```
  TypeError: Frame 0 (u'719ff6da-ac33-4273-a2bc-6cb9b4...) does not
  support the buffer interface.
  ```

References: 5596379

eventmq/utils/classes.py

@@ -362,7 +362,7 @@ def recv_multipart(self):
         msg = self.zsocket.recv_multipart()
 
         # Decode bytes to strings in python3
-        if type(msg[0] in (bytes,)):
+        if sys.version[0] == '3' and type(msg[0] in (bytes,)):
             msg = [m.decode() for m in msg]
 
         # If it's not at least 4 frames long then most likely it isn't an