Improve permissions

Improve permissions

Improve packaging for Systemd.

Systemd was complaining about the service, telling:

juin 22 07:25:42 common_box systemd[1]: Configuration file
   /usr/lib/systemd/system/smack-rules.service is marked executable.
   Please remove executable permission bits.
   Proceeding anyway.
juin 22 07:25:42 common_box systemd[1]:
   Configuration file /usr/lib/systemd/system/smack-rules.service
   is marked world-inaccessible.
   This has no effect as configuration data is accessible via APIs without restrictions.
   Proceeding anyway.

Change-Id: Ie09e6a8ee0668b8c0014a3e5d339eb744b44c86c
Signed-off-by: José Bollo <jose.bollo@open.eurogiciel.org>