Ie8 accordion

Currently the accordion causes both ie8 and ie9 to lock up when you click a panel header. This hack skips animations in CollapsableMixin which works, but there must be a cleaner way to employ ReactTransitionEvents, right?
Hey, sorry for the delay. Seems like ReactTransitionEvents should expose a check to see if it's supported.

What about just checking for node.addEventListener rather than sniffing the UA?