New artwork

[mediaminister]

This pull request includes:

• new artwork
• function to delete old artwork from cache on first run of 2.2.0 version

[dagwieers]

My only concern here was the move from a .jpg to a .png because the documentation specifically talks about it being fanart.jpg. But looking at what exists in the official repository:

[dag@moria xbmc-repo-plugins]$ grep '.jpg</fanart>' */addon.xml | wc -l
109
[dag@moria xbmc-repo-plugins]$ grep '.png</fanart>' */addon.xml | wc -l
4

So I think we're good :-)

[mediaminister]

kodi-addon-checker didn't complain and saving vector art in jpg format is completely insane.