Say I have the object:

```
var Foo = DS.Model.extend({
  name    : DS.attr('string'),
  is_baz  : DS.attr('boolean')
});

```

During a session with the application, foo objects will be added and deleted, and will toggle their `is_baz` flag.

In a template, I need to show the list of all Foos that are `is_baz == true`. As the list of foo objects in the store mutates, the displayed list should update dynamically. Hopefully using the store as the single source of information about foos.

I haven't any seen examples of observing a recordArray for changes to the contained objects. How would we go about doing this in ember?