Exposes fanart as skin properties for slideshows, etc

Uses the XBMC database to grab all fanart from media items and put it into a skin property for use by skins/slideshows as previous version of XBMC allowed. http://forum.xbmc.org/showthread.php?tid=166572 https://github.com/robweber/script.grab.fanart https://github.com/robweber/script.grab.fanart The MIT License all