New wr admin charts

This PR adds stacked percentage charts to the WR admin to visualize participants' betting allocations.

![screenshot from 2014-12-01 14 46 42](https://cloud.githubusercontent.com/assets/59292/5252132/fb0be424-7968-11e4-9093-d97f96c60e98.png)

It also includes some usability fixes to the game:
- Focus "Next Round" button when appropriate
- Inputs respond to return key
- Bankrupt modal closes when you click 'play again'