Add Geocoder::ServiceUnavailable to the readme
Add Geocoder::ServiceUnavailable to the readme

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