title: Update (re-deploy) existing azure webjob
body: <p>I created an on-demand webjob. In the management portal there is no option to upload a new zip, to update it.<br>
  I can delete the existing webjob and create a new one, but I would like to keep my logs.<br>
  Is there any way to re-deploy it, overriding the old version, maintaining the logs?</p>