Start listener in a background thread

    Returns:
      address of the Server as a tuple of (host, port)

def start(self):
    """Start listener in a background thread

    Returns:
      address of the Server as a tuple of (host, port)
    """
    server_sock = self.start_listening_socket()

    # hostname may not be resolvable but IP address probably will be
    host = self.get_server_ip()
    port = server_sock.getsockname()[1]
    addr = (host, port)
    logging.info("listening for reservations at {0}".format(addr))

    def _listen(self, sock):
      CONNECTIONS = []
      CONNECTIONS.append(sock)

      while not self.done:
        read_socks, write_socks, err_socks = select.select(CONNECTIONS, [], [], 60)
        for sock in read_socks:
          if sock == server_sock:
            client_sock, client_addr = sock.accept()
            CONNECTIONS.append(client_sock)
            logging.debug("client connected from {0}".format(client_addr))
          else:
            try:
              msg = self.receive(sock)
              self._handle_message(sock, msg)
            except Exception as e:
              logging.debug(e)
              sock.close()
              CONNECTIONS.remove(sock)

      server_sock.close()

    t = threading.Thread(target=_listen, args=(self, server_sock))
    t.daemon = True
    t.start()

    return addr