Fix Ruby 1.8.7 incompatibility.

Need to determine how necessary this encoding is, and how to do it
properly in 1.8.7.

lib/geocoder/lookups/maxmind.rb

@@ -29,7 +29,10 @@ module Geocoder::Lookup
     def parse_raw_data(raw_data)
       # Maxmind just returns text/plain as csv format but according to documentation,
       # we get ISO-8859-1 encoded string. We need to convert it.
-      CSV.parse_line raw_data.force_encoding("ISO-8859-1").encode("UTF-8")
+      if raw_data.respond_to?(:force_encoding)
+        raw_data = raw_data.force_encoding("ISO-8859-1").encode("UTF-8")
+      end
+      CSV.parse_line encoded
     end
 
     def reserved_result