A nice timing stats report.

Review Request #2825 — Created Sept. 15, 2015 and submitted — Latest diff uploaded

jsirois, patricklaw

Consists of line charts showing aggregate workunit timings by date,
and a drilldown table with further detail per sub-workunit.

Note that, obviously, the timings likely change dramatically day-to-day,
depending on how many builds the user runs, and what they do.
So it's hard to come up with any generally useful report idiom.
This report represents how much time a user is spending in various
parts of Pants during a day, which I hope is a rough indicator of sources
of user dissatisfaction (given that we assume that the ideal time for
any build operation is zero), and can inform optimization decisions.

Also makes the pants server serve a favicon, as the JS console errors
on lack of favicon were driving me nuts, and, amazingly, there's no reliable
way for a page to tell a browser to stop requesting favicons, other than
to provide one...

[PS: Reviewers - since this doesn't affect builds at all, and is just a nice-to-have page in the pants server, feel free to rubber-stamp the review if you're not JS-proficient.]

A large amount of manual testing. We're not set up for automated UI testing just yet.
It shouldn't be affected, but CI passes, just for the hell of it: https://travis-ci.org/pantsbuild/pants/builds/80520823.