My Library -> (artist)id's missing

[tadly]

In case a user uploaded songs to Play Music it might be that google can't match existing
artists and therefore we end up without artistId
This will probably hold true for albumId's as well.

We also have to consider that uploaded media is poorly named (and without proper id3-tags) meaning we might end up without artist-/album name's

[tadly]

A proper implementation still needs to be made.
0f23371 just ignores missing id's for now so the addon stops crashing.

How to solve this issue properly I'm still not sure about as everything I can think of right now
feeels more like a hack :/