deprecate Geocoder::Result::Nominatim#class method

lib/geocoder/results/nominatim.rb

@@ -79,6 +79,11 @@ module Geocoder::Result
          polygonpoints display_name class type stadium]
     end
 
+    define_method 'class' do
+      warn "Method 'class' is deprecated. Use 'place_class' instead"
+      @data['class']
+    end
+
     response_attributes.each do |a|
       unless method_defined?(a)
         define_method a do