Code review comment for lp:~aacid/unity8/preview_progress

I think the documentation needs a \brief headline (then a new line with the rest of the description, to be consistent)

Question, is total of Ubuntu.DownloadDaemonListener 0.1 always > 0?

163 + spy.target = previewProgress
semicolon

Also, considering all the issues we had with signalSpy, I'd rather clear it after
compare(args[2], progressjsonFinish);, and compare with 1 then.