Change the import script for 2013 to use ESRI Shapfiles instead of GeoJSON

Annoyingly, the version of GDAL on the production server seems
to be too early to be able to import GeoJSON and it's a pain to
upgrade.  So, instead, I've converted the data to ESRI shapefiles
with ogr2ogr and this commit changes the import script to load
shapefiles instead.