autotest: Add suite support for testbeds.

Adds basic suite support for Android testbeds. Note this does not
support SSP and only uses the Autotest code that is currently
pushed to prod.

* Added a new provision test (provision_TestbedUpdate).
* Added a basic suite to test this workflow.
* Updated the parsers to allow for multiple boards.
* Had to adjust the provision control_segment to allow commas
  in the key-value labels.

BUG=chromium:628415,chromium:628036
TEST=./site_utils/run_suite.py --board=dragonboard-2 \
--build=git_mnc-brillo-dev/dragonboard-eng/3014741,\
git_mnc-brillo-dev/dragonboard-eng/3014741 \
--suite_name=dummy_testbed --pool='' --run_prod_code

Change-Id: Ica04911974d69498877b9cedb9cefc4a5d0bcdd5
Reviewed-on: https://chromium-review.googlesource.com/360663
Commit-Ready: Simran Basi <sbasi@chromium.org>
Tested-by: Simran Basi <sbasi@chromium.org>
Reviewed-by: Kevin Cheng <kevcheng@chromium.org>
Reviewed-by: Dan Shi <dshi@google.com>
diff --git a/server/cros/provision.py b/server/cros/provision.py
index 6080cf5..9eb414a 100644
--- a/server/cros/provision.py
+++ b/server/cros/provision.py
@@ -212,6 +212,8 @@
                               'tag': 'rw_only'}),
         ANDROID_BUILD_VERSION_PREFIX : actionables.TestActionable(
                 'provision_AndroidUpdate'),
+        TESTBED_BUILD_VERSION_PREFIX : actionables.TestActionable(
+                'provision_TestbedUpdate'),
     }
 
     name = 'provision'