Add back in latestChange, but more clearly mark it as a notification.
Merge pull request #564 from jaycee/change-notifications

Add back in latestChange, but more clearly mark it as a notification.

`latestChangeDescription` is the piece of data previously provided to the
to the template to make notifications work. Because it wasn't clear it was a notification,
it was incorrectly identified as redundant code and removed. This adds it back in,
with tests, and renames it to make its purpose clearer.