[0.11.257.B] cherrypick: use crossystem for developer mode and nonchrome detection

[0.11.257.B] cherrypick: use crossystem for developer mode and nonchrome detection

Adds crossystem use for developer mode detection and nonchrome detection.
[This allows systems with missing or damaged TPMs or bad firmware to
 go through recovery as nonchrome systems.]

(testing in progress)
TEST=create a devkeys x86-alex image, boot it and install it in both modes
     same thing for x86-mario
     boot x86-mario, goto a shell, run crossystem mainfw_act to ensure it never says nonchrome
     again for a nonchrome system
BUG=chromium-os:13399, chromium-os:8762
Change-Id: I538fe37fbed29537132da15c844b75ce726634bf

Review URL: http://codereview.chromium.org/6724018
(cherry picked from commit 28966b0a8e746fd882fdd781d6a201d688dcde3d)

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=29f505a

[Randall Spangler, 2011-03-23 19:14:09]

LGTM