TryGhost/Ghost — pull request #3628 by novaugust (2014-08-06 14:35:33+00:00)
Title: Add open class to popover buttons

Ref#3603
- Popover Buttons now have an `open` class applied to them when their popover is open
- The open class is removed from the popover button at the start of the popover's fadeout
- Consolidated common code into popover-mixin