Adds author name for new playlist, removes some prints
Naming of playlist, new playlist JSON

* Naming of the newly created playlist is no more based on random numbering, but
on actual playlist id: playlist_<playlist.id>
* The returned json of the newly created playlist is no more encapsulated into a
"playlist" entry, but all the playlist fields are returned directyl at
top-level: { "<playlist-fieldN>" : "<valueN>", etc. }
FIX global name 'Person' undefined