SoundCloud

[UltimateRiff]

I know it's mentioned in #5, but I figured I'd start up a ticket with a link to the API docs at least~

https://developers.soundcloud.com/docs

a couple notes about SoundCloud:

• some title cleanup might be needed? especially stuff like "[FREE DL IN DESCRIPTION]", which is quite common
• GTIN and ISRC are optional metadata
• playlists and albums are both implemented as "sets", and perhaps both should be importable? I know a lot of artists don't properly set the type for what's pretty clearly an album (even Taylor Swift has some such examples)
• Creative Commons Licenses should be detected and added when present
• track downloads are optional and should be detected (sometimes with a Buy link that goes to a file hosting service like MediaFire or MEGA, or with a DL LINK IN DESCRIPTION)