Stop OpenVPN process group
        :param timeout: time in seconds to wait for process to stop
        :return:

def stop(self, timeout=None):
        """
        Stop OpenVPN process group
        :param timeout: time in seconds to wait for process to stop
        :return:
        """
        if not timeout:
            timeout = self.timeout
        os.killpg(os.getpgid(self.process.pid), signal.SIGTERM)
        self.thread.join(timeout)
        if self.stopped:
            logging.info("OpenVPN stopped")
            if self in OpenVPN.connected_instances:
                OpenVPN.connected_instances.remove(self)
        else:
            logging.error("Cannot stop OpenVPN!")
            for line in self.notifications.split('\n'):
                logging.warn("OpenVPN output:\t\t%s" % line)