Make "/etc/os-release" available

Generating the initramfs images by "mkinitcpio" requires the "/etc/os-release" file to be already present as a symlink to "/usr/lib/os-release", which is normally performed by systemd in the "/usr/lib/tmpfiles.d/etc.conf" file. Thus, ensure that the required symlink already exists in the rootfs directory before "pacstrap" or "pacman" are executed.

At the same time, perform some improvements and code cleanups, as spotted while going through the source code. Also, change the timestamp format in the generated log filenames to a more common (and more readable) format.

Signed-off-by: Dragan Simic dsimic@manjaro.org