Configure web demo to work with TURN server

When connecting to video across NATs on the web demo running on a remote server, video turns up blank and audio/chat do not work. Still works well when on the same NAT.

I modified web/client/main.js to have

``` javascript
var configuration = {
"iceServers": [
{
"url": "turn:104.236.XXX.XXX",
"username": "test",
"credential": "1234"
}
]
};
```

And on 104.236.233.141, I have Google's TURN server running (https://code.google.com/p/rfc5766-turn-server/) invoked like

turnserver --no-tls --no-dtls -b /etc/turnuserdb.conf -f -v

When I press the call button, the turn server seems to be doing things, like

> 2953: IPv4. Local relay addr: 104.236.233.141:61639
> 2953: session 000000000000000012: new, username=<>, lifetime=600
> 2961: session 000000000000000012: user <>: incoming packet ALLOCATE processed, success
> 2963: session 000000000000000011: user <>: incoming packet BINDING processed, success

and the node demo server is outputting like

> users in session 32cf24: 1
> @32cf24 - fd6045df left.
> users in session 32cf24: 0
> @45a596 - b231749c joined.
> @45a596 - 2470eba8 joined.
> @45a596 - 2470eba8 => b231749c :
> @45a596 - 2470eba8 => b231749c :

This happens on Chrome: 42.0.2311.90 (64-bit), and on NativeDemo and HybridDemo

I'm not sure if I've misconfigured the TURN server, or there is something additional I should be doing in the Web demo setup.