When implementing this spec two critical problems were found:
* PXEBoot.validate requires instance image parameters, so we cannot
use it during inspection.
* PXEBoot.prepare_ramdisk tries to configure DHCP/PXE environment,
which clashes with inspector's one and requires VIFs to be present.
This change also marks the inspector part as done in 8.0.0 and
puts the unsolved problems into the text for anyone who will want
to revive the spec.
Finally, the RFE link is changed to storyboard.
Change-Id: I5a2920b1416889aaaed725e4cb669c505c2ed0bf
53984da2e4