[importer] Drop the_geom_webmercator column if present, before georeferencing
[importer] Drop the_geom_webmercator column if present, before georeferencing

UCL-ShippingGroup/cartodb-1,nuxcode/cartodb,CartoDB/cartodb,future-analytics/cartodb,dbirchak/cartodb,DigitalCoder/cartodb,bloomberg/cartodb,UCL-ShippingGroup/cartodb-1,raquel-ucl/cartodb,CartoDB/cartodb,raquel-ucl/cartodb,bloomberg/cartodb,nuxcode/cartodb,codeandtheory/cartodb,UCL-ShippingGroup/cartodb-1,nuxcode/cartodb,DigitalCoder/cartodb,raquel-ucl/cartodb,nyimbi/cartodb,codeandtheory/cartodb,splashblot/dronedb,thorncp/cartodb,future-analytics/cartodb,thorncp/cartodb,future-analytics/cartodb,CartoDB/cartodb,nyimbi/cartodb,bloomberg/cartodb,nuxcode/cartodb,splashblot/dronedb,thorncp/cartodb,bloomberg/cartodb,raquel-ucl/cartodb,nyimbi/cartodb,codeandtheory/cartodb,DigitalCoder/cartodb,nuxcode/cartodb,splashblot/dronedb,bloomberg/cartodb,nyimbi/cartodb,CartoDB/cartodb,nyimbi/cartodb,future-analytics/cartodb,future-analytics/cartodb,splashblot/dronedb,DigitalCoder/cartodb,dbirchak/cartodb,codeandtheory/cartodb,dbirchak/cartodb,thorncp/cartodb,thorncp/cartodb,CartoDB/cartodb,codeandtheory/cartodb,DigitalCoder/cartodb,UCL-ShippingGroup/cartodb-1,raquel-ucl/cartodb,dbirchak/cartodb,UCL-ShippingGroup/cartodb-1,dbirchak/cartodb,splashblot/dronedb