Add Skill Rating To Player Global Statistics

[jakejgordon]

Base off of average rank vs. expected rank. E.g. in a 7 player game with 3 winners, 3 second place, one last place, your chance of 1st place is 3/7.

This algorithm will have to be fairly sophisticated and weigh games with a large number of players more heavily than 2-player games. For example, Winning a 10-player free for all should be worth much more than winning a single 2-player game of War.