replace rdio_simple for requests_oauthlib

* The nonce is still very buggy. For some unknown reason Rdio keeps
  saying my nonce is duplicated, even when it's always unique. Just
  repeating the request seems to work, though.

* requests_oauthlib is pretty cool and will allow us to better organize
  our code. But for now I've just hacked it in the current code just to
  see if works.