Submit a new Apple Touch icon for MediaWiki.org

This patch provides a new Apple Touch icon for
MediaWiki.org. It comes as a 152x152 px square
to satisfy the needs of iPad devices with the
new Retina display.

Also, I'm submitting it because MatmaRex said
it was ugly as sin.

Change-Id: Id41906c9ef01e7076562d9154977fc0ac7a9e081