Add division separation into the Arena formula.

This is, of course, on a seasonal basis. Assign a numerical value to each tier, 1 being Iron and 5 being Onyx, and raise this number exponentially. This will give players who are in the higher divisions a much greater degree of separation. Onyx players will be placed above Gold because their value of 5 will be far greater than 3 when raised exponentially. I'm not entirely sure what power to raise it to, though, as I'm not aware of the values going into the rest of the formula, but it should be enough to separate the tiers significantly.