Real Screensaver via Tampermonkey

I have a screensaver feature for HABPanel, waiting code review from @ysc

Basically with this, all you have to do is create a dashboard page with whatever you want in it (like your camera feed, etc), and when the screensaver kicks in, it will switch to that dashboard. And you can configure which dashboard to go back to (when screen saver stops, like from a click)