Add post-stop-dhcp-release hook script and dnsmasq-utils package

The dnsmasq-utils has a dhcp_release utility that will be used by
the post-stop-dhcp-release script when a container that has a
reserved IP is stopped or destroyed to release the container's
DHCP lease.
Disable emacs auto-save and backups for root user

The auto backup of files in particular was creating problems
with dnsmasq when backups of dhcp-hosts.conf and of the leases file
existed. Dnsmasq was actually usng the contents of the backups
in addition to the originals.