code: def update(title, unsubscribe_page, confirmed_opt_in,
        confirmation_success_page, unsubscribe_setting="AllClientLists",
        add_unsubscribes_to_supp_list=false, scrub_active_with_supp_list=false)
        options = { :body => {
          :Title => title,
          :UnsubscribePage => unsubscribe_page,
          :ConfirmedOptIn => confirmed_opt_in,
          :ConfirmationSuccessPage => confirmation_success_page,
          :UnsubscribeSetting => unsubscribe_setting,
          :AddUnsubscribesToSuppList => add_unsubscribes_to_supp_list,
          :ScrubActiveWithSuppList => scrub_active_with_supp_list }.to_json }
        cs_put "/lists/#{list_id}.json", options
      end
docs: Updates this list.
   title - String representing the list title/name
   unsubscribe_page - String representing the url of the unsubscribe
     confirmation page
   confirmed_opt_in - A Boolean representing whether this should be a
     confirmed opt-in (double opt-in) list
   confirmation_success_page - String representing the url of the
     confirmation success page
   unsubscribe_setting - A String which must be either "AllClientLists" or
     "OnlyThisList". See the documentation for details:
     http://www.campaignmonitor.com/api/lists/#updating_a_list
   add_unsubscribes_to_supp_list - When unsubscribe_setting is
     "AllClientLists", a Boolean which represents whether unsubscribes from
     this list should be added to the suppression list
   scrub_active_with_supp_list - When unsubscribe_setting is
     "AllClientLists", a Boolean which represents whether active sunscribers
     should be scrubbed against the suppression list