title: send formData using dropzone.js on sendingmultiple
body: <p>The dropzone.js documentation/wiki doesn't say how to send form fields.</p>
  
  <p>I just read about the <a href="https://developer.mozilla.org/en-US/docs/Web/API/FormData/FormData" rel="noreferrer">FormData object</a> and it says how to populate the object with the form fields. The problem is that populating the object with the whole form won't get the data send, but if I append the form fields one by one they'll get sent...</p>
  
  <p>This works:</p>
  
  <pre><code>formData.append('name', jQuery('#name').val());
  </code></pre>
  
  <p>This doesn't:</p>
  
  <pre><code>var myForm = document.querySelector('form');
  formData = new FormData(myForm);
  </code></pre>
  
  <p>The first example will send the <code>#name</code> field but the second won't send anything (just the files).</p>
  
  <p>How can I trigger that? I'd like to make dropzone send the whole form along the files (both in the same request).</p>
  
  <pre><code>init: function() {
      var myDropzone = this,
          submitButton = document.querySelector("[type=submit]");
  
      submitButton.addEventListener('click', function(e) {
          e.preventDefault();
          e.stopPropagation();
          myDropzone.processQueue();
      });
  
      myDropzone.on('sendingmultiple', function(data, xhr, formData) {
          // this will get sent
          formData.append('name', jQuery('#name').val());
          // this won't
          var myForm = document.querySelector('form');
          formData = new FormData(myForm);
      });
      myDropzone.on('successmultiple', function(files, response) {
          //window.location.replace("/home");
      });
      myDropzone.on('errormultiple', function(files, response) {
          alert(response);
      });
  }
  </code></pre>