How to: Server Manager
Supported [Manage Multiple Users](https://github.com/shadowsocks/shadowsocks/wiki/Manage-Multiple-Users) API:

- `add` - Starts a server instance
- `remove` - Deletes an existing server instance
- `list` - Lists all current running servers
- `ping` - Lists all servers' statistic data

NOTE: `stat` command is not supported. Because servers are running in the same process with the manager itself.

```bash