title: Updating model in angular doesn't cause updating components variables in Angular
body: <p>I have problem with understand why Angular doesn't decorate variables in my component if I update it in controller:
  <code>ctrl.myVar.attr = "decorated_" + ctrl.myVar.attr;</code>
  after click on button in following plunker example:
  <a href="http://plnkr.co/edit/cV18oB64oqiO9fYHrhCz?p=preview" rel="nofollow noreferrer">http://plnkr.co/edit/cV18oB64oqiO9fYHrhCz?p=preview</a></p>