change default mode, allow to overwrite this change

[PopiBrossard]

Dear maintainer,

This pull request allows to change permissions (in chmod way only) of the systemd and executable created files on Redhat.

This also change the default mode of systemd file to remove warning messages in the logs:

May  6 18:36:00 foo systemd[1]: Configuration file /etc/systemd/system/sysfsutils.service is marked world-inaccessible. This has no effect as configuration data is accessible via APIs without restrictions. Proceeding anyway.
May  6 18:37:00 foo systemd[1]: Configuration file /etc/systemd/system/sysfsutils.service is marked executable. Please remove executable permission bits. Proceeding anyway.

Regards