Split "readonly rootfs / tmpfs" parts of original olpc patch into new
'readonly' patch; plus add additional support for preserving changes to
/etc/ssh, /etc/sysconfig/i18n, /etc/timezone, /var/lib/dbus/machine-id,
and /var/lib/random-seed.
Add "pretty boot" support: bring up localhost before rhgb-client is
invoked; some additional calls to rhgb-client; make sure that we
cleanly exit pretty boot if interactive boot mode is invoked.
