In the current "rally scoring" used in volleyball, each serve results in one
point, either for the serving team or for the receiving team. Whoever wins
the point is the server on the next point. The winning team is the first
team to win at least 15 points and be at least 2 points ahead of the other team.
Suppose that two teams are playing a game, and that they are evenly matched.
On each point, whichever team serves has a fixed probability, probWinServe,
that they will win the point. (Of course, the receiving team will win the point with
probability 1.0  probWinServe.)
Create a class Volleyball that contains a method win that is given sScore (the
current score of the serving team), rScore (the current score of the receiving
team), and probWinServe. It returns the probability that the serving team will
win the game.
