Overdue changes for gs_check.py

This fixes:
  1) Error when testing bucket access. Root does not
     have the correct priviledges to access gs, so the
     check must be run as the moblab user.

  2) Add a check warning when we are configured to access
     an internal bucket.

Change-Id: I7e38d1d641f341fe50cbdcc93f93a61245207d9a
Reviewed-on: https://chromium-review.googlesource.com/362385
Commit-Ready: Simran Basi <sbasi@chromium.org>
Tested-by: Simran Basi <sbasi@chromium.org>
Reviewed-by: Simran Basi <sbasi@chromium.org>
(cherry picked from commit f8b1019f4f7f498ad2cb3c077fcc895570308370)
Reviewed-on: https://chromium-review.googlesource.com/362651
Reviewed-by: Krk Mohan <krk@google.com>
1 file changed