Improved Antagonist Scaling

![scaling](https://cloud.githubusercontent.com/assets/3828067/4120673/0c800bd2-32b4-11e4-97cc-7070ae8f8a48.png)

To allow for saner antagonist scaling at high-population while still accomodating low-population rounds.

The PR changes the formula to thus:
Antagonists = min ( population / (2* coeff ) + 2, population / coeff )

For traitor, this means
Traitors = min ( population / 10 + 2, population / 5 )

Default traitor scaling coeff has been reduced to 5