message: change user_playlist_follow_playlist return type
diff: @@ -678,8 +678,11 @@ impl Spotify {
  map.insert("public".to_owned(), public.into());
  let mut url =
  String::from(format!("users/{}/playlists/{}/followers",playlist_owner_id,playlist_id));
  - self.put(&mut url, Value::Object(map));
  - Ok(())
  + match self.put(&mut url, Value::Object(map)) {
  + Ok(_) => Ok(()),
  + Err(e) => Err(e),
  + }
  +
  }
  