devserver: Add quick_provision stage artifact.

BUG=chromium:779870
TEST=curl "http://${ds}/stage?archive_url=gs://chromeos-image-archive/${build}&artifacts=quick_provision"

Change-Id: I1b8949fdff93cba06d19a5264e1485741dd253bc
Reviewed-on: https://chromium-review.googlesource.com/751791
Commit-Ready: David Riley <[email protected]>
Tested-by: David Riley <[email protected]>
Reviewed-by: Xixuan Wu <[email protected]>
2 files changed