Fix a couple regressions for general comments.
Review Request #8502 — Created Oct. 27, 2016 and submitted
The addition of a feature for general comments had a couple small issues. First
of all, we want to enable this feature by default, so that it's available for
people using release-3.0.x without any special configuration. Second, the
plumbing for the option through to the review dialog (to add the "Add Comment"
button) wasn't using the right name.
Was able to use general comments on my devserver again.