Create amarok.xml

Tested on Chakra 2014.02 "Curie", Amarok 2.8.0
After a few months of using amarok, this cleaner erased 1.5 MiB from the album cover cache.
home page: http://amarok.kde.org/
Popularity stats: The amarok irc channel (irc.freenode.net #amarok) typically has around 90 people.