This also adds a set of files in the qubes/ directory that
are meant to be copied to the /boot partition.
Issue #154: for ease of upgrading Qubes, the script should
live on /boot instead of in the ROM. This requires a GPG
signature on the startup script to avoid attacks by modifying
the boot script.
Issue #123: this streamlines the boot process for Qubes, although
the disk password is still not passed in correctly to the initrd
(issue #29).
This does not address issues #110 of how to find the root device.
The best approach is probably disk labels, which will require
special installation instructions.
