When changing data, notify properties will change

[dadah89]

Problem: data is a hash, and Ember doesn't notify when nested properties of a hash change. That means for example, if a resource has one embedded association, and after a fetch some property of this association changes, the cacheable property (association name) won't be notified and will still return an old value. i.e.:

var obj = Em.Object.create({ 
  data: { association: { name: 'foo' } }, 
  observesHash: function() { console.log('changed!'); }.observes('data')
});
obj.setPath('data.association.name', 'bar');
// => Class {__ember1352744516303_meta: Object}
obj.setPath('data', {});
// => changed! 
// => Class {__ember1352744516303_meta: Object}

/cc @shajith

[shajith]

I like this. Will see if I can run this by @staugaard.

[staugaard]

Looks good