Update ubuntu templates

Update ubuntu templates

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>