title: Dropzone "addedfile" is not fired when adding images programatically
body: <p>I want to add <code>checkbox</code> to dropzone images so that I can upload only the selected ones. I am going to add a <code>checkbox</code> next to each image when the <code>addedfile</code> event is fired.   </p>
  
  <p>I am using the following method to <a href="https://stackoverflow.com/q/27171958/69537">programmatically add images to dropzone</a>:</p>
  
  <pre><code>var mockFile = { name: "image.jpg", size: 12345 };
  imgUrl = "http://example.com/image.jpg"
  myDropzone.options.addedfile.call(myDropzone, mockFile);
  myDropzone.options.thumbnail.call(myDropzone, mockFile, imgUrl);
  </code></pre>
  
  <p>The problem is that the "addedfile" event is not fired for images added this way:</p>
  
  <pre><code>myDropzone.on("addedfile", function(file) {
      console.log("file added!"); // this line is never printed
  });
  </code></pre>
  
  <p>But if added an image by manually clicking on <code>dropzone</code> and selecting a file, the above event would fire. Why is this event not fired in the first case?</p>