No of players squashed

Changes implemented with the commit: 
  - The CSS for the number of players input field was removed as it is not needed.
  - The number of players input is now in the form of a radio button.
  - `settings.js` now has the `number_of_players` as a property.

The result looks like this: 

![screen shot 2014-04-06 at 12 00 01 am](https://cloud.githubusercontent.com/assets/4560085/2624469/08a14d5c-bd41-11e3-8224-bd2f5783d648.png)

@cvan 's previous comments on the number of players input field are addressed in this PR.