Use rich text for Review Bot reviews.
Review Request #8763 — Created Feb. 17, 2017 and submitted — Latest diff uploaded
This change enables the use of rich text in comments (which is currently not
used by any tools), and more usefully, uses rich text to improve the format of
the warning when the number of comments posted has been clipped.
Ran a tool that created more than 30 comments and saw the resulting body-top
was shown with markdown formatting.