Updated README to mention GPX dumper
Updated README to mention GPX dumper

shamyyl/Geocoder,stof/Geocoder,jmcclell/Geocoder,heatery/Geocoder,geocoder-php/Geocoder,fluxoft/Geocoder,Koc/Geocoder,tylerhebel/Geocoder,collmomo/Geocoder,ankr/Geocoder,mubassirhayat/Geocoder,pecopeco/Geocoder,xabbuh/Geocoder,geocoder-php/Geocoder,misterion/Geocoder,arunlodhi/Geocoder,Nyholm/Geocoder,svrdlic/Geocoder,Nyholm/Geocoder,svrdlic/Geocoder,jollysean/Geocoder