Update show.api.rsb

Add the field updated_on when fetching the issue journals

app/views/issues/show.api.rsb

@@ -59,6 +59,7 @@ api.issue do
         api.user(:id => journal.user_id, :name => journal.user.name) unless journal.user.nil?
         api.notes journal.notes
         api.created_on journal.created_on
+        api.updated_on journal.updated_on
         api.private_notes journal.private_notes
         api.array :details do
           journal.visible_details.each do |detail|