code: def read_content (self):
          
          if self.is_directory():
              data = get_index_html(get_files(self.get_os_filename()))
              if isinstance(data, unicode):
                  data = data.encode("iso8859-1", "ignore")
          else:
              data = super(FileUrl, self).read_content()
          return data
docs: Return file content, or in case of directories a dummy HTML file
          with links to the files.