Allow to pass option :empty_tag_value to Nori via local options

.gitignore

@@ -2,6 +2,7 @@
 .byebug_history
 .DS_Store
 .yardoc
+.ruby-version
 doc
 rdox
 coverage

lib/savon/options.rb

@@ -495,6 +495,11 @@ def response_parser(parser)
       @options[:response_parser] = parser
     end
 
+    # Instruct Nori how to convert empty tags.
+    def empty_tag_value(empty_tag_value)
+      @options[:empty_tag_value] = empty_tag_value
+    end
+
     # Instruct Savon to create a multipart response if available.
     def multipart(multipart)
       @options[:multipart] = multipart

lib/savon/response.rb

@@ -150,7 +150,8 @@ def nori
         :convert_tags_to             => @globals[:convert_response_tags_to],
         :convert_attributes_to       => @globals[:convert_attributes_to],
         :advanced_typecasting        => @locals[:advanced_typecasting],
-        :parser                      => @locals[:response_parser]
+        :parser                      => @locals[:response_parser],
+        :empty_tag_value             => @locals[:empty_tag_value]
       }
 
       non_nil_nori_options = nori_options.reject { |_, value| value.nil? }