Set up the root shell

Make /bin/bash the root shell and copy usable configuration from
/etc/skel.
Do not copy /var to tmpfs

this was a bad idea (whole rpmdb is there)
grub.cfg: default to the 'minimum RAM' mode
Install extra packages from extra_packages/

The packages from the selected PLD repository may be not enough.
'gpm' package added to the 'rescue' module
Pass list of selected languages to RPM

save a few MB on i18n files