Add "Last Update By" to Dashboard & ReviewRequest Dashboard

Review Request #3159 — Created June 23, 2012 and discarded — Latest diff uploaded

Review Board
I thought the "Last Updated By" column would be a useful feature to ReviewBoard and turns there was already an issue opened for it. (

I originally added the "Last Updated By" to dashboard but I thought it would be useful for the Review Request Dashboard as well.

Please let me know if there is a better implementation to this.
Ran the ReviewBoard test suite and did a lot of manual testing.