plans: Add test plan v2 support for rendering

testplan2html.py script now supports both v1 (with requirements) and v2
test plans. The output is still a set of static HTML files that can be
rendered further to PDF document.

Change-Id: I2a0dfabded65d1dfa18f543a42718f54ae4c6014
Signed-off-by: Milosz Wasilewski <milosz.wasilewski@linaro.org>
2 files changed