replace unattened upgrades with cron-apt.

The ubuntu security repos, fpf and tor repo are listed in `/etc/apt/security.list`

Every night at 4am the apt-get update for the repos listed in `security.list`

If a package requires a reboot it creates the /var/run/reboot-required file.

Every night at 5 am if that file exists the system will reboot.
removed the unattended-upgrades that were replaced by the cron-apt
re-added disabling swap with `swapoff -a`
Merge pull request #717 from dolanjs/cron-apt

Cron apt