add "started" timestamp on the current operations on Recent Uploads and Downloads

[zooko]

I see a list of current uploads and downloads, it looks like this:

Active Operations:
Type 	Storage Index 	Helper? 	Total Size 	Progress 	Status
mapupdate MODE_READ 	6ju7xitmj6gfrd6bf6ghn3nlju 	No 	-NA- 	0.0% 	Sending 1 initial queries

However, later when I reload the "recent uploads and downloads" page, there's no way to figure out which of the completed/failed reads is that one:

Active Operations:
Type 	Storage Index 	Helper? 	Total Size 	Progress 	Status
No active operations!

Recent Operations:
Started 	Type 	Storage Index 	Helper? 	Total Size 	Progress 	Status
09:34:22 07-Nov-2012 	mapupdate MODE_READ 	6ju7xitmj6gfrd6bf6ghn3nlju 	No 	-NA- 	100.0% 	Finished
09:21:51 07-Nov-2012 	mapupdate MODE_READ 	6ju7xitmj6gfrd6bf6ghn3nlju 	No 	-NA- 	100.0% 	Finished

If the "active operations" list included the started timestamp, then I would be able to tell which of the later, finished operations describes that earlier, active operation. (Provided that all otherwise identical operations started at different times.)