Custom renderer for lightbox

![1406548510](https://cloud.githubusercontent.com/assets/708296/3720045/28ae7906-164e-11e4-8842-e483b702d34e.png)

Related Waldorf PR (to make sure we don't bork interests): https://github.com/lonelyplanet/waldorf/pull/1365
Yeah, as mentioned above, *how* the content gets rendered is an app specific decision so all I'm trying to do is make sure that the ability to do this works.