[HOLD][#53420683] Updated the "Act on behalf of another user" page on the knowledge base.

Relies on https://github.com/AllPlayers/brochure.allplayers.com/pull/129 and https://github.com/AllPlayers/brochure.allplayers.com/pull/130

• Updated screenshots
• Changed up some text
• Renamed to "Edit child info" (this is what the page was actually about to being with)
• Moved to be under "Manage your account" instead of "Create account"

![2013-11-04_1047](https://f.cloud.github.com/assets/2251119/1466419/e5d34d0e-4570-11e3-95e6-0ea233a011e7.png)