Fix Revolving Door Caption on Chrome 24 Ubuntu 12.04 and Chrome 29 OSX 10.8.4

The Revolving Door Caption was only being triggered on hover over the left-half of the element in Chrome (on Ubuntu and OSX) see video: http://www.youtube.com/watch?v=z5LEkIe00x8

Moving the transform perspective to the child elements seems to have fixed this, and, is seemingly more performant. I rolled over the transition a few times and recorded frames in Chrome Dev tools

old: http://cl.ly/image/183v2x280A0m
new: http://cl.ly/image/0c0k373s3P2N

Summary of commit:

* Move perspective from parent element to child elements
* Change rotation direction for straight-forward approach
* Modify transition to use $effeckt-caption-transition-duration variable rather than magic number