[#62] Correctly update slave count when drops below 1.
[#62] Correctly update slave count when drops below 1.

mbeacom/locust,bugsduggan/locust,bugsduggan/locust,cgoldberg/locust,pan1cz/locust,pmdarrow/locust,fordhurley/locust,jaume-pinyol/locust,jaume-pinyol/locust,pmdarrow/locust,locustio/locust,santiavenda2/locust,mbeacom/locust,jaume-pinyol/locust,pan1cz/locust,mbeacom/locust,santiavenda2/locust,fordhurley/locust,TZer0/locust,fordhurley/locust,TZer0/locust,mbeacom/locust,pan1cz/locust,heyman/locust,locustio/locust,bugsduggan/locust,cgoldberg/locust,locustio/locust,TZer0/locust,pmdarrow/locust,cgoldberg/locust,locustio/locust,santiavenda2/locust