Copy serial_utils.py from factory repo

This module provides methods and classes to handle serial devices
which would be useful in implementing an abstraction class for
bluetooth evaluation kits next.

BUG=chromium:575551
TEST=None

Change-Id: I734fd78f6651bd1f0c7e1a63ef807b871c1996ff
Reviewed-on: https://chromium-review.googlesource.com/322060
Commit-Ready: Shyh-In Hwang <josephsih@chromium.org>
Tested-by: Shyh-In Hwang <josephsih@chromium.org>
Reviewed-by: Wai-Hong Tam <waihong@chromium.org>
1 file changed