refactor blacklistCurrentPlaylist into blacklistPlaylist

[brandonocasey]

Currently blacklistCurrentPlaylist can blacklist arbitrary playlists by passing a playlist on the error object passed into it. This is confusing because the function makes it seem like it will only blacklist the current playlist and because the playlist variable inside the function is named currentPlaylist. We should refactor all of this code into a blacklistPlaylist function, deprecate the old function via a 1-time warning, and use the new function internally.

[gkatsev]

Would be nice to switch to ignorePlaylist or blockPlaylist or excludePlaylist.