Live image ppc and ppc64 support

[Jeremy Katz]

Okay, I've finally gotten around to merging dwmw2's changes for ppc
support in livecd-creator.  First off, thanks for getting the ball
rolling.

Of course, now the fun part is that it would be nice to be able to
support both ppc and ppc64 with the images.  There are a few barriers to
that as it currently stands.  

The biggest is probably that the ppc and ppc64 kernels currently
conflict.  The actual vmlinuz files as well as the modules end up under
the same paths.  Without that fixed, it's a bit of a non-starter.  Maybe
it finally makes sense to make the paths depend on uname -m in addition
to uname -r?  Other ideas?

If we get that fixed, the livecd-creator side of things shouldn't be
that bad to do.  Mainly just making it so that we handle multiple
kernels (which kanarip has a patch for, just need to finish getting it
into a merge-ready state) and then a little of the 3264 logic out of
anaconda's scripts.

Jeremy