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
The ppc config files were missing from the live config_files directory
and ppc needs the correct lib directory so lmc has been switched to use
ArchData driven from the installed kernel arch.
Resolves: rhbz#1102318