Packaging MediaWiki for Debian

Over the past few months I've been working on an updated Debian package for MediaWiki. After working with Luke, Faidon, Moritz, and a few others, we now have a mostly working package! It's being developed in Gerrit (the mediawiki/debian repository), so it hopefully will get more visibility, and we can keep it in sync with current development.

If you're interested in testing, I've uploaded it to people.wikimedia.org for now.