Add progress bars to reports.

A nice to have feature would be progress bars for measurement and trials on reports.
This could give an idea of when an experiment is done.
I think it should be doable from the info we already store in the db.
Only issue is the bar might be a bit misleading, since we may have only 10% of snapshots left to measure but this doesn't mean the time the experiment takes is 90% done because the last snapshots may be most expensive to measure (not a progress bar maven, but I assume this problem is faced by all progress bars).