Cut down size of repo

I was trying to do some work on a slow connection and wondering why it takes so long to upload recipes, then I discovered that the file `cookbooks/jenkins/files/default/jetty-distribution-8.1.11.v20130520.tar.gz` is 90% of the diskspace, and I'm not even using Jenkins! I think it would be better to fetch this file off a static host somewhere rather than keeping it in the repo. What do you think?