These were apparently lost in the transition to livemedia-creator. livecd-creator added them in it's code, and lmc based its live config files on the the boot.iso configs which do not include it (on purpose).
This adds a new livemedia-creator argument, --extra-boot-args, which can be used to add arguments to the kernel command-line in the templates.
This adds the aarch64 template, and the grub2-efi config file to the live template directory. Resolves: rhbz#1369014
