selective syncing

[simon-weber]

Having a way to set specific syncing settings on particular playlists is something that's been brought up a few times. Mostly it'd be helpful in reducing load by avoiding unwanted syncs.

The easiest way to go about this would probably be to mark playlists to not sync. Syncing playlists at different periods would be more useful, but more complicated (since there's currently only a single sync timer).