* (bug 11179) Include image version deletion comment in public log

* (bug 11179) Include image version deletion comment in public log
Append comment, if present, to the deletedrevision text. This matches undeletion behavior.
To pretty that up, removed the final period from the default deletedrevision message; it didn't look good with the following colon, and even when alone it's inconsistent with other usage, we usually don't have a period there.