Add support for /me/* endpoints to the client credentials flow

[owensco]

I was getting a 401 hitting the /me endpoint. That led me to #147 and #331 where it became clear that the client credentials flow only supports access to public information like tracks and playlists.

Considering I am using the client and secret key associated with an app that's tied to my account (to generate the token), it would be great if I could fetch my own data.

At the very least, please remove these endpoints from the Swagger documentation, which make it look like these endpoints are supported via the credentials flow: https://developers.soundcloud.com/docs/api/explorer/open-api#/me/get_me

Thank you!