title: find and findAll return an empty array
body: <p>In an ember 1.13.3 app, I have this route : </p>
  
  <pre><code>import Ember from 'ember';
  
  export default Ember.Route.extend({
    model: function() {
      return this.store.find('skill');
    }
  });
  </code></pre>
  
  <p>And this model :</p>
  
  <pre><code>import DS from 'ember-data';
  
  export default DS.Model.extend({
    name: DS.attr('string'),
    description: DS.attr('string'),
    link: DS.attr('string'),
    acquired_skills: DS.hasMany('users', { async: true, inverse: 'acquired_skills' } ),
    searched_skills: DS.hasMany('users', { async: true, inverse: 'searched_skills' } )
  });
  </code></pre>
  
  <p>This is the result returned by the api :</p>
  
  <pre><code>{"skills":[{"id":1,"name":"Ember","description":"JS Framework","link":null}]}
  </code></pre>
  
  <p>The array is empty. I can check it with this <code>console.log(this.store.find('skill').get('length'));</code> and I have 0.</p>
  
  <p>What's wrong?</p>