Callback "done" does not get triggered when using rgb

I was doing something like this:

```
@colorPicker = colorjoe.rgb "color-picker", [....], [...]

@colorPicker.on "done", (color) ->
  ...
```

But then I realized that this does not work and throws an error. I dug a bit in the source code and noticed that it needed a minor fix. Not sure if this works in all cases, so I'll let you be the judge of that. Hope this helps.