title: element ui upload component not sending stream data
body: <p><strong>Image Upload using el-upload component</strong></p>
  
  <p>I am getting 204 no content response from the server </p>
  
  <pre><code>   el-upload(
          action="https://s3-us-west-1.amazonaws.com/stage.greenausm.com",
          :mulitple="false",
          :data="xhrData"
          :show-file-list="false", :on-success="handleAvatarSuccess",
          :before-upload="beforeAvatarUpload",
        )
  </code></pre>
  
  <p>The request  to the server does not have the image data</p>
  
  <p>------WebKitFormBoundaryksB7UzZHz8SWLdPk
  Content-Disposition: form-data; name="file"; filename="img.jpg"
  Content-Type: image/jpeg</p>
  
  <p>------WebKitFormBoundaryksB7UzZHz8SWLdPk--</p>
  
  <p>How can I get the component to send image data</p>