Returns the path with the query parameters escaped and appended.

def _get_relative_path(self):
    """Returns the path with the query parameters escaped and appended."""
    param_string = self._get_query_string()
    if self.path is None:
      path = '/'
    else:
      path = self.path
    if param_string:
      return '?'.join([path, param_string])
    else:
      return path