Permissions on service file

Hi there!

Thanks for improving the tuxedo module! Now my installation has another TODO item scrapped off. :)

But I have a quick question... Why does the service need executable permissions (755) on the systemd service file? ( The installation / building section in the README suggest that, and the AUR package does it.) Normally service files are 644, and systemd will complain about it if it is executable. Is there any reason to it?