Using generic downloader script for Windows

[joergi]

same as #39 but for Windows

• [x] use it for books
• [ ] use it for regular issues

[joergi]

@Jaykul - if you wanna have a look... feel free to assign yourself

the issues in the Downloader are here:

https://github.com/joergi/downloader/issues/1 https://github.com/joergi/downloader/issues/3

[joergi]

The script is now used to download the windows books. maybe the regular issues can use it too!