Rename 'ubuntu' template to 'lucid'

Add new maverick and natty templates, which do much less tweaking
of the environment.  These should only be used on a kernel which
supports sysfs tagging for /sys/class/net, as udev will be running
in the container.

The natty template needed to slightly change the installed packages
for dhclient to be correclty installed.
Signed-off-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>