PythonJS backend

This should work, but I was unable to get hello_world_example.py to work because of a syntax error:

uncaught SyntaxError: Unexpected identifier localhost/:82
Uncaught ReferenceError: init_communication is not defined 

on line 82: the && gets escaped for some reason.

```
                if (!reconnectAttempt &amp;&amp; !timedOut) {
                    if (self.debug || ReconnectingWebSocket.debugAll) {
                        console.debug('ReconnectingWebSocket', 'onclose', url);
                    }
                    self.onclose(event);
                }
```