Add diff_image script to compare factory/autotest directories in
images.

BUG=chrome-os-partner:12676
TEST=process_utils_unittest.py, Manual for diff_image

Change-Id: I467a8121ab6bc57014b29ccdbaccf5250fdd2728
Reviewed-on: https://gerrit.chromium.org/gerrit/30536
Tested-by: Jon Salz <jsalz@chromium.org>
Reviewed-by: Jon Salz <jsalz@chromium.org>
5 files changed