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.
Resolves: rhbz#1689314
Make kernel args the same in every config.
Put 'quiet' at the end of the line - it's usually the first thing a user removes when debugging.
Fill missing product versions in.
Distinguish between 'install' (installation media) and 'start' (live media).
live media isn't exactly the same as the Anaconda install media. Right
now this amounts to needing a root= cmdline argument but in the future
there may be other differences.
This also reverts 5437557846 on the new copies of the templates.
