title: mongoose delete all documents in collection
body: <p>from the id I recovers in a collection of documents : </p>
  
  <pre><code>exports.dropWithDocumentId = function(req,res) {
      Flux.loadByDocumentId(req.params.id,function(err,flux){
          if (err) { res.sendStatus(500); return; }
  
  
          console.log(flux) ;
          res.json(flux);
      });
  }
  </code></pre>
  
  <p><strong>and it gives me the following result</strong>:</p>
  
  <pre><code>[ { _id: 55a37838363ea5c00913cb4b,
      texte: 'testtt',
      nomUtilisateur: 'user1',
      formation: 5587d9b96c861a800f6d6563,
      diplome: 5587e7acb90c3e581a0393ac,
      __v: 2,
      tags: [],
      documents:
       [ { document: 55a37824363ea5c00913cb4a,
           modele: 'Fichier',
           _id: 55a37838363ea5c00913cb4c } ],
      type: 1,
      commentaires:
       [ { _id: 55a3790ff6c0f588056b5b82,
           user: 5587e7acb90c3e581a0393ac,
           prest: 5587d9b96c861a800f6d6563,
           texte: 'aaaaaaaaaaaa',
           date: Mon Jul 13 2015 10:38:39 GMT+0200 (Paris, Madrid (heure d'été))
  ,
         { _id: 55a37906f6c0f588056b5b80,
           user: 5587e7acb90c3e581a0393ac,
           prest: 5587d9b96c861a800f6d6563,
           texte: 'aqqqqqq',
           date: Mon Jul 13 2015 10:38:30 GMT+0200 (Paris, Madrid (heure d'été))
   ],
      date: Mon Jul 13 2015 10:35:04 GMT+0200 (Paris, Madrid (heure d'été)) } ]
  </code></pre>
  
  <p><strong>Now I want to delete all the documents in this collection from the id</strong> :</p>
  
  <pre><code>exports.dropWithDocumentId = function(req,res) {
      Flux.loadByDocumentId(req.params.id,function(err,flux){
          if (err) { res.sendStatus(500); return; }
  
          flux.forEach( function (doc) {
  
              doc.remove();
            });
          //console.log(flux.type) ;
          res.json(flux);
      });
  }
  </code></pre>
  
  <p>but it does not work !!
  help me</p>