Add wrapper script for easy signing of firmware
Add wrapper script for easy signing of firmware

Thought I might as well put this is in the repo since I use it very often.

Change-Id: Iecbb2340dce1522b15aab8eefb3b2c346cb7c24f

BUG=none
TEST=manually signed an image.

Review URL: http://codereview.chromium.org/6698014

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