This is a temporary hack to allow cros_mark_as_stable to work outside
the chroot. Eventually, we'll re-write the code to use optparse.
BUG=5412
TEST=Verified the cros_mark_as_stable now works outside the chroot.
Change-Id: Ife1f7aeadb70ba004d3928a9c71d6e95c042833d
Review URL: http://codereview.chromium.org/3037046