title: loopback include with two models
body: <p>This current code is working :</p>
  
  <pre><code>  app.models.AvionPiloteAutorisation.find({
      "where": {
        "idAvion": avion.idAvion
      },
      "include": ["pilote"]
    }, function(err, pilotes) { ... }
  </code></pre>
  
  <p>But this :</p>
  
  <pre><code>  app.models.AvionPiloteAutorisation.find({
      "filter": {
        "where": {
          "idAvion": avion.idAvion
        },
        "include": {
          "relation": "pilote"
        }
      }
    })
  </code></pre>
  
  <p>fail. 
  It's suppose to be the same, right ?</p>
  
  <p>I'm trying to add some information using related model 'Utilisateur'</p>
  
  <pre><code>  app.models.AvionPiloteAutorisation.find({
      "filter": {
        "where": {
          "idAvion": avion.idAvion
        },
        "include": {"relation": "pilote", "scope": {"include": ["utilisateur"]}}
      }
    })
  </code></pre>
  
  <p>What am I doing wrong ?</p>
  
  <p>Thanks.</p>