systemd-systemctl: Add preset capability

systemd-systemctl: Add preset capability

systemd has presets as described here

http://lists.freedesktop.org/archives/systemd-devel/2011-July/002830.html

This patch will let distros define presets file
which will override the enable/disable specified
by recipes.

systemctl preset without any argument will run presents
on all services

systemctl preset service1 service2 will run presets on
specified pervice.

something like enable * or disable *
would mean that all services will be either enabled or
disabled by default.

If no user-presets are specified then 'enable' is default

systemd allows basic globs but we do not implement them
except '*'

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>