Add an option to Auto-Sync an entire playlist folder with a device

[DonDan]

The idea is that one could be able to set a "playlist folder" and not only single playlists to sync with a device.

This way every playlist included in the folder would be synced. And most importantly also every new playlist that would be created in that designated folder would also be synced without the need to change any settings in the "Preferences > Devices" menu.   

Cheers and keep up the great work!