Need to produce driver update ISO

[Matt Zimmerman]

We should produce a driver update ISO as part of the standard build, which can be used for testing the driver update machinery (and perhaps use the same system to create actual driver update CDs)

The layout should be, e.g.:

mizar:[/tmp] find /mnt
/mnt
/mnt/ubuntu-drivers
/mnt/ubuntu-drivers/2.6.22-14-generic
/mnt/ubuntu-drivers/2.6.22-14-generic/linux-backports-modules-2.6.22-14-generic_2.6.22-14.10_i386.deb

<codename>-drivers-<arch>.iso seems like a reasonable name.