Implement simulators leaderboard

This implements #703
This currently looks like this:
![topsimulatorstable](https://cloud.githubusercontent.com/assets/396538/2688538/229c0478-c2a9-11e3-8b7d-d1e81148e2fb.jpg)

I still need to figure out how to add my strings for internationalization. I'm also concerned I'm returning more of the user objects than needed: is this a problem?