Support for Ubuntu and Windows

Windows Command prompt command for locking the machine

```cmd
C:\Users\duksis> rundll32.exe user32.dll,LockWorkStation
```

On Ubuntu gnome possibly 

```bash
$ gnome-screensaver-command -l
```

sources: 
https://askubuntu.com/questions/184728/how-do-i-lock-the-screen-from-a-terminal
https://www.youtube.com/watch?v=-bl8iPgt-2w