[autotest] Add in hwid library for label generation.

This library is the base part of a Cros Label mechanism that will use
hwid to generate new labels.  The key file will be stored in a private
location in another cl.

BUG=chromium:571087
TEST=unittests

Change-Id: I10e40a8c2f4134c04e84c3b26d53bb70092c08b4
Reviewed-on: https://chromium-review.googlesource.com/321924
Commit-Ready: Kevin Cheng <[email protected]>
Tested-by: Kevin Cheng <[email protected]>
Reviewed-by: Kevin Cheng <[email protected]>
2 files changed