lxc-ubuntu{-cloud}: Config layout tweaking

This commit tweaks the layout of the config file for the Ubuntu templates.

With this, we now get a clear network config group, then a path related group,
then a bunch of random config options and the end of the config is apparmor,
capabilities and cgroups.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>