Greed game koan

@jjballano recently posted his version of the Greed game, as part of his learning experience with Ruby Koans. As I am following that very same path, I thought it could also be worth for me to share my implementation of Greed for people to comment on it.

The code could surely be much prettier since I am still trying to get my head around ruby block-passing, among others, so comments (and patches!) are welcome.

UPDATE: The code seems to update automatically to the latest version on github, you can find the original here.