Make today's data update dataset when you click refresh

[octopicorn]

Add a button to refresh today's data.

• add api call to fetch latest numbers from today (same one to ESRI used by JH)

• need to write logic for:

  • if numbers are for the same date as the last data column in timeseries, we will UPDATE the last point of each timeseries
  • if numbers are for the next date past the end of the timeseries, we will APPEND the last point of each timeseries

• fetch latest numbers on page load

• add button that you can click to trigger a new fetch&update

• add spinner while fetching