Add a choice of a 2-up/2-down ranking algorithm to the League Session setup

Currently the League Session setup allows the choice of a 1-up/1-down reranking algorithm when setting up a League Session.  My club players believe that this doesn't introduce enough movement in the ladder each week, when played once a week.  We would like a 2-up/2-down reranking algorithm to maximize movement up and down.  It would be similar to the 1-up/1-down just moving 2 players up and 2 players down instead.