Authentication link on https://mopidy.com/ext/soundcloud/ is broken

[lucbrinkman]

Clicking the authentication link on https://mopidy.com/ext/soundcloud/ loads an otherwise empty page stating "Oops, something went wrong."

Tested on four different browsers spread over three different devices.

[kingosticks]

It's been a long time since I tried to use mopidy-soundcloud I confess. I'm sorry to say I think it might be broken following Soundclouds's OAuth changes. There was some work at #123 (comment) and then I think we need to finish our support for PKCE. I'm not sure where all this got left, we should have updated the readme to stop wasting people's time. Sorry about that.