Fixes OID warnings when using PostgreSQL
Fixes OID warnings when using PostgreSQL

Postgres correctly identifies OIDs when BEARING and DISTANCE contain
numerical values. It fails to identify OID for a NULL type.

This patch explicitly sets an OID type for NULLs when running in
PostgreSQL environment.

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