rss: fix xbmc.org feed

http://feeds.xbmc.org has been created so that we can prevent this in the
future. It is now a CNAME using the "MyBrand" feature at feedburner, which is
up and running again after the latest news entry.

With this set, we change we can modify the feed at any time in the future.
Merge pull request #2440 from theuni/feedburner

rss: fix xbmc.org feed