artwork MinimServer constants

[x-stefan]

Sometimes you can't see the forest for the trees - thank you for your hint.
For the "Tag View" I'm now using the kid3 icon from wikimedia:
https://commons.wikimedia.org/wiki/File:Kid3_logo.svg

I have already the CD icon and also a triple CD icon in use and didn't want a third CD like icon.
But meanwhile I realized, that the default behavior of MinimServer to show the album cover is exactly what I need. This is due to the fact, that I have a few albums where the <albumname>.jpg is different to the embedded album cover of the files.