Users should be able to create a priority list for where they would like covers to be fetched from.
For example, no 1 priority could be the one embedded in the file's ID3 tag. If that is not found, fall back to 2nd priority item which could be an online database (Amazon, Itunes, Tunein)
We could also make a "custom album art" item and get a bit creative here. Like display a certain album art for a certain Artist.