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
Hmmm... I'm thinking it might've been clearer if I renamed it `data.content` -> `content` (i.e. the same as L129-130 above it).

The idea being that as far as _this component_ is concerned, it always just receives content and if not, the `renderContent` function needs to be used to make sure whatever format it comes back as in the app renders ok.