LU-8384 scripts: Add scripts to systemd for EL7

LU-8384 scripts: Add scripts to systemd for EL7

When rebooting a lustre client where Lustre filesystem is still
mounted, the shutdown hangs. This patch create a systemd service
that unmount the Lustre filesystems and unload the Lustre modules
when system is shutdown.

Test-Parameters: trivial

Lustre-change: https://review.whamcloud.com/21457
Lustre-commit: 495deddfbb43f247b2fa9dd2da5743abc89cd862

Change-Id: I1cfe84684e23b8861743241dfbc4d6e320ace4a6
Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Signed-off-by: Gregoire Pichon <gregoire.pichon@atos.net>
Signed-off-by: Nathaniel Clark <nclark@whamcloud.com>
Reviewed-by: Gu Zheng <gzheng@ddn.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/34503
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>