Need UI testing: inconsistent behavior in Firefox, Chrome, Safari

[shentonfreude]

Changing into full screen behaves differently on these 3 browsers, and we pop out of full screen on some events in Chrome now.

At Pycon, this presentation mentioned tools for doing visual automated testing against CSS, Javascript, Responsive design:
https://us.pycon.org/2014/schedule/presentation/199/

The UI tools was Needle: https://github.com/bfirsh/needle

We'll have to figure out how to make different satellite positions over time not factor into visual difference detection: we only want to notice UI regressions.