cts: Added html output to cts

When you run a test suite, cts will now save your
results for the suite/dut combo as a basic html page

BRANCH=None
BUG=None
TEST=Manual
- Connect dut, th
- Build/flash desired test suite
- Run './cts -r' to run tests
- Open /tmp/cts_results/<board_name>/<test_suite>.html
- You should see a table with test names/results

Change-Id: Id3de3bd7833be1bc5dde437c516db411aac47579
Reviewed-on: https://chromium-review.googlesource.com/362091
Commit-Ready: Chris Chen <twothreecc@google.com>
Tested-by: Chris Chen <twothreecc@google.com>
Reviewed-by: Randall Spangler <rspangler@chromium.org>