Shell out to lsb_release instead of using the Ohai attribute node['lsb']['codename']

The attribute is empty during the first converge. Don't know why.
Tell Vagrant to boot the VM with 2 cores and 2 GB of RAM
Revert "Tell Vagrant to boot the VM with 2 cores and 2 GB of RAM"

This reverts commit a786a05379b3e4e6d709a0722adaf030895d3507.
Vagrantfile: stop using a slow mirror in favor of Debian's CDN

http://cdn.debian.net/debian/ is blazingly fast
Merge remote-tracking branch 'upstream/master'