Fix a few packaging bugs, including and especially a temporary patch to our upstart script to mount cgroups

This needs to get into 0.9.0 if possible (to make sure cgroups work properly).

One of the other major additions here is that Debian will actually get "/var/log/docker.log" as it should - the only reason we didn't have this before is because Ubuntu 12.04's start-stop-daemon is too old to have `--no-close`, but we use upstart on Ubuntu so it doesn't actually matter! :)