Fix incorrect metadata in place

Quite a lot of the tags for Composer in Spotify are wrong (often confused with Artist). It would great to flag corrections immediately as you can do with incorrect listings on Amazon.

Spotify Legend

Changing the status of this to "duplicate idea" and then refering it to another thread that says nothing is going to happen doesn't change the fact that the metadata is really screwed up. You should be able to do at least as good as wikipedia