title: django admin: save image like base64
body: <p>I'd like to upload image through django admin panel, but I need to save it as a base64 string in database
  How could I do it?
  +</p>
  <ol>
  <li>I would like to see image in admin</li>
  <li>DB may move someday and it will be better to save just base64 string, so I won't depend on some file structure (as if I'll store original images somewhere)</li>
  </ol>
  <p>ps. I have django 2.2.6 version</p>