Add a few more commands to help debug verified boot.
Add a few more commands to help debug verified boot.

BUG=chromium-os:8160
TEST=manual

Refer to http://code.google.com/p/chromium-os/issues/detail?id=8237 for
testing instructions.

To specifically test for this change, the log file should contain the string
(and output from running)

  "od -Ax -tx1 hd_kern_a.blob | head"

Change-Id: I910d1f0e41c03afd34bfa5139825e479d7124d71

Review URL: http://codereview.chromium.org/4242001

geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,ionave/seismograph,coreboot/vboot,ccaapton/vboot_reference,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,marineam/seismograph,ccaapton/vboot_reference,ionave/seismograph,acorn-marvell/vboot_reference,acorn-marvell/vboot_reference,marineam/seismograph,coreboot/vboot,ccaapton/vboot_reference,marineam/seismograph,ionave/seismograph,coreboot/vboot,ccaapton/vboot_reference,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,marineam/seismograph,geekboxzone/mmallow_external_vboot_reference