Fixed "GanttEditor: Error saving data on the server side: No authentication found ('')" bug.
  Apparently Chrome sometimes sends out PUT XHTTP calls without cookies.
  So ]po[ then correctly identifies a non-authenticated session.
  As a workaround, I have added auth_token authentication in the SenchaPreference store,
  so that the calls are authenticated, even if the cookies should disappear for some
  reason.