First steps in script changes

[Jeremy Katz <katzj redhat com>]

If you've been watching the commits, you'll have noticed a number of small
and obvious fixes going in for the various scripts in the scripts/ directory
to take into account environment changes over time.  The following set 
of patches is the more controversial set of things to start reducing the
option set for buildinstall and also making the calling conventions
between buildinstall and upd-instroot and mk-images a little bit cleaner.

Where I'm headed with this is being able to have a "make an instcd.iso"
script which will create the iso-to-replace-rescuecd.iso.  This iso
will have the kernel bits along with the second stage to make it easier for
people.  I'll probably also be killing off boot.iso and perhaps bootdisk.img
in the process of doing so.

Comments appreciated both on the first steps and the longer-term.

Jeremy