Add "Private Session" to the Settings#52

I would like to listen to audiobooks via “private session”. This would ensure that spotify won’t sync with my last.fm and the audiobooks don’t fuck up the yearly review etc.

Hello, very good idea that I also already looked into. Unfortunately for the moment there is no way for my app to set the private mode in spotify :(
But I’ll open an issue with spotify about that, we never know, maybe they’ll make it possible.