[Release-1.0] Add / delete members part of an existing playlist

[InukVT]

I noticed that you can't add members to playlists. Sometimes it would be nice to surprise my loved once with a dope mixtape, but have it prepared weeks ahed of times. Or my mixtape could be so lit, that my loved ones want to participate.

[adilanchian]

I like your examples a lot here. This is on the roadmap for release 1.0, looks like phase 2 beta