Update status pane as the user types

Update status, remark and advice link as the user types
according to the following rules.
  1. When a subunit loads and the tutor is in READY state,
     display the READY status.
  2. Display a 'Restart' link as soon as the user types
     something and the state of the tutor changes from READY to
     RUNNING.
  3. When the user makes an error, display the ERROR status.
  4. When the user completes typing the subunit text, display a
     remark and an advice link.