Autotest: Be able to grab the lab status and add it to run_suites

Now that the lab status page is up, we need to be able check when the
lab is not up and in that case stop run_suite from being able to schedule
jobs.

BUG=chromium-os:37095
TEST=Changed the lab status page to lab is closed and ensure that run_suites
     did not schedule the job if that occured.

Change-Id: I0e0f80e872c4b94f5d6148eb5634298ff7263cbc
Reviewed-on: https://gerrit.chromium.org/gerrit/39449
Reviewed-by: Simran Basi <sbasi@chromium.org>
Tested-by: Simran Basi <sbasi@chromium.org>
Commit-Queue: Simran Basi <sbasi@chromium.org>
diff --git a/client/common_lib/error.py b/client/common_lib/error.py
index 54a08cd..ca1a2c7 100644
--- a/client/common_lib/error.py
+++ b/client/common_lib/error.py
@@ -560,6 +560,11 @@
     pass
 
 
+class LabIsDownException(Exception):
+    """Raised when the Lab is Down"""
+    pass
+
+
 # This MUST remain at the end of the file.
 # Limit 'from error import *' to only import the exception instances.
 for _name, _thing in locals().items():