adds null_value method for code reuse
adds null_value method for code reuse

guavapass/geocoder,davydovanton/geocoder,jaigouk/geocoder-olleh,AndyDangerous/geocoder,StudioMelipone/geocoder,rios1993/geocoder,boone/geocoder,rayzeller/geocoder,FanaHOVA/geocoder,ankane/geocoder,tiramizoo/geocoder,3mundi/geocoder,GermanDZ/geocoder,Devetzis/geocoder,sjaveed/geocoder,gogovan/geocoder-olleh,jaigouk/geocoder-olleh,eugenehp/ruby-geocoder,mehlah/geocoder,mdebo/geocoder,rdlugosz/geocoder,malandrina/geocoder,alexreisner/geocoder,aceunreal/geocoder,brian-ewell/geocoder,tortuba/geocoder,epyatopal/geocoder,moofish32/geocoder,gogovan/geocoder-olleh,sideci-sample/sideci-sample-geocoder,andreamazz/geocoder,donbobka/geocoder,mveer99/geocoder,TrangPham/geocoder,jgrciv/geocoder