added parameter nscatimeout to allow for connections with more latency

Hello,

when using this gem and the nsca listener is not on the same machine but in fact on another site, one second of latency sometimes isn't enough. I've added the parameter nscatimeout (which defaults to the initial value of 1 if not specified) to allow for more latency.

This is my first pull request so I'm glad for any advice, formally and otherwise.

-Armin