Authorization url outdated

[johnro]

Hi team! Thanks for the great library, I'm using in a project now, and I noticed that the @accounts.authorization_url seems like its outdated.

The url returned is https://accounts.spotify.com/oauth/authorize?client_id=... which gives an error when trying to access it.

https://accounts.spotify.com/authorize? seems to work.

See #65

Thanks!

[bih]

This is merged :)