Orbit: Added prefixed transition-duration properties

This will resolve #5140, which I've replicated in Mobile Safari on a first gen iPad (iOS5). Without this patch animations do not run, which means that the [transitionEnd event](https://github.com/zurb/foundation/blob/master/js/foundation/foundation.orbit.js#L454) does not fire, which breaks the slider after the initial transition has occurred.

I've not tested in older versions of Opera or Firefox but I expect this fix improves compatibility for those browsers too.