Add example hooks from Ubuntu package

We've been shipping those two hooks for a while in Ubuntu.
Yesterday I reworked them to use the new environment variables and
avoid hardcoding any path that we have available as a variable.

I tested both to work on Ubuntu 13.04 but they should work just as well
on any distro shipping with the cgroup hierarchy in /sys/fs/cgroup and
with ecryptfs available.

Those are intended as example and distros are free to drop them, they
should however be working without any change required, at least on Ubuntu.

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