title: Ajax form post not posting input type with file
body: <p>"i have simple form and posting it with ajax, but i am not able to get the $_FILES in php script"</p>
  
  <pre><code>&lt;form id="submitForm" method="post" enctype="multipart/form-data" &gt;
       &lt;input type="file" name="file"  /&gt;
       &lt;input type="text" name="name" /&gt;
      &lt;/form&gt;
  </code></pre>
  
  <p>below is ajax code,tell me where i am mistaken</p>
  
  <pre><code>$.ajax({
                  url: '&lt;?php echo base_url(); ?&gt;getter/addItemRow',
                  type:"POST",
                  data:$('#submitForm').serialize(),
                  context: $('#table')
                  }).done(function(data) {
                    this.prepend(data);
                  });
  </code></pre>
  
  <p>below is php code line</p>
  
  <pre><code>print_r(var_dump($_FILES));
  </code></pre>
  
  <p>this is returning empty array;</p>