use prebuilt lucid packages

This is how I think you should could build your `.tgz`. Using the latest nightly would be nicer but that would involve parsing http://dl.hhvm.com/ubuntu/dists/lucid/main/binary-amd64/Packages to find the latest one just incase a nightly fails.

You could alternatively compile it. It takes ~1 hour on my 4 core machine. This should be up to date: https://github.com/facebook/hhvm/wiki/Building-and-installing-on-Ubuntu-10.04-LTS