Add class to run multiple configurators at once.

To speed up how long it takes to run apply_settings in a configurator
we have add a class with a thread pool that will processes several at
once.

BUG=None
TEST=Ran it

Change-Id: I15e8bbf9390141b2b7077e6aeaf59352693e36bd
Reviewed-on: https://gerrit.chromium.org/gerrit/39984
Commit-Queue: Kris Rambish <krisr@chromium.org>
Reviewed-by: Kris Rambish <krisr@chromium.org>
Tested-by: Kris Rambish <krisr@chromium.org>
7 files changed