支持证书本地备份、异地恢复，方便一套SSL证书多台设备部署;

[dongfengpo]

1.主设备cert-up.sh backupcurr备份最新证书到backup/current; 2.子设备cert-up.sh backup备份所有证书; 3.复制主设备backup/current到子设备同名目录，cert-up.sh revertcurr;