title: new AjaxUpload start by some other button
body: <p>I'm using the <code>valums.com/ajax-upload</code> plugin. The problem is that it starts uploading as soon as I select a file, I want to start the upload by clicking some other button, so user can change values if they want to.</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;div id="upload" &gt;&lt;span&gt;Upload File&lt;span&gt;&lt;/div&gt;
  &lt;input type="button" name="submit" id="submit" value="Submit" /&gt;
  &lt;span id="status" &gt;&lt;/span&gt;&lt;ul id="files" &gt;&lt;/ul&gt;
  </code></pre>
  
  <p>jQuery:</p>
  
  <pre><code>$(function(){
      var btnUpload = $('#upload');
      var status = $('#status');
      new AjaxUpload(btnUpload, {
          action: 'upload-file.php',
          name: 'uploadfile',  
          autoSubmit: false,
          onSubmit: function(file, ext){
              // if (! (ext &amp;&amp; /^(pdf)$/.test(ext))){ 
              if (!(ext &amp;&amp; /^(jpg|png|jpeg|gif|pdf)$/.test(ext))) { 
                  // extension is not allowed 
                  status.text('Only JPG, PNG or GIF files are allowed');
                  return false;
              }
  
              upload.setData({'example_key': 'value'});
          },
          onComplete: function(file, response) {
              //On completion clear the status
              status.text('');
  
              //Add uploaded file to list
              if (response === "success") {
                  $('&lt;li&gt;&lt;/li&gt;').appendTo('#files').html('&lt;img src="./uploads/'+file+'" alt="" /&gt;&lt;br /&gt;'+file).addClass('success');
              } 
              else {
                  $('&lt;li&gt;&lt;/li&gt;').appendTo('#files').text(file).addClass('error');
              }
          }
      });
  
      $("#submit").click(); ////dont know how to do it.
  });
  </code></pre>