Automate data transfer from Google Spreadsheet to Map

So far the transfer is done by manually exporting the spreadsheet, converting it to GeoJSON and then adding it to the HTML, which isn't ideal.

The workflow should be something along the lines of:

- [ ] People add new point via the tooltip
- [ ] The new point's tooltip changes from form to showing new entry
- [ ] The new entries may be converted to a specifically labelled GH-issue, for reviewing the new data
- [ ] new data is getting merged into the GH repo?
- [ ] This triggers travis-ci to update the geojson