Fix #N/A sporadically appearing in the agency number widgets

- This was caused by Google Spreadsheets running the command to
  import data from the transition spreadsheet and not getting data.
  This made `#N/A` appear for unpredictable lengths of time,
  unpredictably, so this hopefully successfully deals with it by
  querying the spreadsheet every two seconds until the todo and done
  values are no longer `#N/A`, or another variant `#VALUE!`.