Removed use of eval from Lookups::Base#result_class.

Signed-off-by: James McCarthy <james2mccarthy@gmail.com>

lib/geocoder/lookups/base.rb

@@ -87,7 +87,7 @@ module Geocoder
       # Class of the result objects
       #
       def result_class
-        eval("Geocoder::Result::#{self.class.to_s.split(":").last}")
+        Geocoder::Result.const_get(self.class.to_s.split(":").last)
       end
 
       ##