title: ember add an promise to a rsvp promise because of action
body: <p>i have a route that returns several models as such</p>
  
  <pre><code>FriendEnemyRouter
  
  model: function() {
      return Ember.RSVP.hash({
          friends: this.store.find('People', ...),
          enemies: this.store.find('People', ..),
  </code></pre>
  
  <p>On the same router theres an action (Its on the router because it does store 'things')       </p>
  
  <pre><code>actions: {
       findMoreFriends: function(param, param) {
           var newFriends = this.store.find('People', ..); 
           var newPromise = this.controller.get('model'); //OK. Inspecting sees above friends and enemies. What type is it?
  
           model.set("newFriends": newPromise); // throws an exception
           //-- or --
           model.newFriends = newPromise; // no exception but observer (computer property) on the controller is not fired.
       }
   }
  </code></pre>
  
  <p>Ultimately i wish this computed property on the controller to fire</p>
  
  <pre><code> FriendEnemyController
  
    computedNewFriends: function() {
         ....
     ).property('newFriends');
  </code></pre>
  
  <p>What is the procedure for adding new promises to rsvp promises...not even sure the object types...</p>
  
  <pre><code>         model.set("newFriends": newPromise); // throws an exception
           model.newFriends = newPromise; // no exception but clearly doesnt notify observer/property
  </code></pre>