Unwatch chained property with capitalized name

I began a simple application, which consumes a JSON payload and render the response. So my route sets the model to something like this:

```
{
  "Config": {
    "Image": "xxx"
  }
}
```

and my template bind to this value: `<span>{{Config.Image}}</span>`. But if I leave the route, Ember throws an exception: `Uncaught TypeError: Cannot read property 'unchain' of undefined `.
But if I rename "Config" to "config" it works. Do I misunderstood any ember magic or is this a bug?

So I wrote a failing test for chained properties. Can everybody help to get solve the problem, please?