title: Update image using collectionfs
body: <p>I'm using collectionFS to upload an image, the thing is I want my users to be able to upload just one image and then change it(upload a new one).
  I have the part in place to check if an image is already uploaded but the thing is I can't change the image that is in the db, this is the code I have to insert a new image:</p>
  
  <pre><code>'change .myFileInput': function(event, template) {
    FS.Utility.eachFile(event, function(file) {
      var newFile = new FS.File(file);
      newFile.metadata = {
          createdBy:Meteor.userId(),
      }
      Imagess.insert(newFile, function (err, fileObj) {
        if (err){
           // handle error
        } else {
           // handle success depending what you need to do
          var currentUserId = Meteor.userId();
          var imagesURL = {
            "profile.image": "/cfs/files/images/" + fileObj._id
          };
          Meteor.users.update(currentUserId, {$set: imagesURL});
        }
      });
   });
  </code></pre>
  
  <p>I don't know how to change the Imagess.insert to Imagess.update, I have already read the meteor documentation but can't find how to do it. Can anyone suggest a way or some docs where I can learn how to do it?</p>
  
  <p>Thanks in advance!</p>