Nightly installs on chaos_dut machines

The machines with label chaos_dut currently run tests that are kicked
off manually due to the limitation of the chaos chamber.  The machines
should be updated on a nightly basis for the manual testors convenience.

TEST=Device with chaos_dut should have a new image every morning.
BUG=chromium-os:37636

Change-Id: I93c7d85cb8dff67ff438d7080fca997f061795ee
Reviewed-on: https://gerrit.chromium.org/gerrit/40615
Commit-Queue: Stanley Wong <stanleyw@chromium.org>
Reviewed-by: Stanley Wong <stanleyw@chromium.org>
Tested-by: Stanley Wong <stanleyw@chromium.org>
3 files changed