Hookbox breaks when using a websocket enabled browser on a secure connection (https)

Hookbox does not use a valid websocket url when on a secure connection. The issue is on [line 16](http://github.com/mcarter/hookbox/blob/master/hookbox/js_src/hookbox.js#L16) of hookbox.js. 

The protocol for secure websockets is wss://, so that code could be changed to be:

```
url.replace('http://', 'ws://').replace('https://', 'wss://')
```

or
    url.replace(/http(s)?:\/\//, 'ws$1://')
