Scripts for generating boot-to-ramdisk images are now available. These
can be used for example to boot from PXE or from a USB stick, as the
ramdisk are self-contained and do not rely on any block devices after
being loaded into RAM.
The image generation framework has also been slightly cleaned up in
order to better accomodate tarball sets bundling in images.
Change-Id: I65a176832bd0d6954b430fa8305f90af0bd606c1
a7a79fa1f5