def todolist(list_id)
      response = Logan::Client.get "/projects/#{@id}/todolists/#{list_id}.json"
      Logan::TodoList.new response.parsed_response.merge({ :project_id => @id })
    end
def todolist(list_id)
      response = Logan::Client.get "/projects/#{@id}/todolists/#{list_id}.json"
      Logan::TodoList.new response.parsed_response.merge({ :project_id => @id })
    end
get an individual todo list for this project from Basecamp API

 @param [String] list_id id for the todo list
 @return [Logan::TodoList] todo list instance