Don't detect empty query.

Instead detect further up the chain (before calling the Lookup).

lib/geocoder/lookups/base.rb

@@ -13,7 +13,6 @@ module Geocoder
       # for reverse geocoding.
       #
       def search(*args)
-        return [] if args[0].nil? || args[0] == ""
         if res = results(args.join(","), args.size == 2)
           res.map{ |r| result_class.new(r) }
         else