Create onboarding modal [Fixes #76917104]

![screenshot 2014-08-28 19 05 56](https://cloud.githubusercontent.com/assets/1783869/4084343/e94943f4-2f07-11e4-8c46-5a05538f6e31.png)

ping @fatihacet 
Also why don't you use `JView` class here. IMO, there is lots of `.addSubView` calls here. You can use `pistachio` and create headline, footer like elements via html string. I mean,

```
pistachio: ->
    """
       <div class="top-container">
            <div class="video-placeholder">
    """
```

and so on..