Prevent onWeatherChange from bouncing

[wg4568]

https://github.com/wg4568/splinter/blob/7e9a6ea32a1fffaf0ab6af6b2facd58941b2e274/java/splinter/src/net/gardna/splinter/handlers/WorldWeatherHandler.java#L40-L50

This event fires twice, since the receiving server fires it's own weatherChangeEvent when told to change the weather (I think)