Fix an XSS vulnerability in the reviews dropdown.

The reviews dropdown had a bad vulnerability where it would assume the
user's full name is valid HTML. This allowed the user to craft a script
tag that would be executed every time the name appeared in the dropdown.

This vulnerability exists in 1.6.x, 1.7.x, and the in-development 1.8.
There are no known attacks in the wild.

This was reported by Craig Young at Tripwire.
Release Review Board 1.6.17.