add a lobby algorithm that finds the fairest teams

http://forums.faforever.com/viewtopic.php?f=42&t=16989

This could be used to create a starting point and then players can balance their starting locations (air, front, navy etc) after the algorithm runs

The idea is to take the players rating (or true skill, or a value that represents the how strong a player is) and create teams evenly as possible in the lobby.

Example
Players in lobby
player 1 - 700
player 2 - 783
player 3 - 843
player 4 - 953
player 5 - 1100
player 6 - 1253
player 7 - 1360
player 8 - 1593
player 9 - 1904
player 10 - 2599

Outcome
team 1
player 10 - 2599
player 7 - 1360
player 5 - 1100
player 2 - 783
player 1 - 700

team 2
player 9 - 1904
player 8 - 1593
player 6 - 1253
player 4 - 953
player 3 - 843

difference of 4