get_queue assumes the presence of attributes on queue items.

[c-nixon]

get_queue in core.py often fails with an Attribute error when a track from soundcloud is on the playlist.

Replacing

track.creator,
track.title,
track.album,

with

getattr(track, "creator", ""),
getattr(track, "title", ""),
getattr(track, "album", ""),

on lines 436:438

fixes the problem, but this is a bit messy.

I'm happy to put in a PR for this, but would like suggestions as what people think is the best to fix it.