Clarify or reduce requested Spotify permissions

[Abdull]

Without knowing more the reasoning behind the requested permissions, I find too much is being requested for authorization.

Can you provide the reasoning and try to limit the scope?

[zachwinter]

Oh man – good call. These are leftover from the Beta, which I intended on being a full-fledged Spotify client in the browser.

[spinningmonkey]

I had the same concern. Created a pull request to remove the Users categorized scope.
#77