platform2: add colorized output support when running tests

BUG=chromium:312931
TEST=Run tests, see colorized output for PASS/FAIL/filter warnings

Change-Id: I0d3bd7215fb4a941adef724f8c8e530bfd092eaf
Reviewed-on: https://chromium-review.googlesource.com/182890
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Liam McLoughlin <lmcloughlin@chromium.org>
Tested-by: Liam McLoughlin <lmcloughlin@chromium.org>
1 file changed