[HOLD][#53420683] Updates the "Add a child during group registration" page.

Relies on https://github.com/AllPlayers/brochure.allplayers.com/pull/129.

![1](https://f.cloud.github.com/assets/2251119/1501324/b9de30e4-4889-11e3-98fb-ac1ba94929d3.png)


![2](https://f.cloud.github.com/assets/2251119/1501326/c07b69e4-4889-11e3-8cd3-a1a067fcc404.png)