Update check_zones_in_sync
Update check_zones_in_sync

This change was necessary to get it running on Ubuntu 14.04 LTS
Gem versions:
nio4r (1.2.1)
celluloid-io (0.17.3)

Ruby version:
ruby1.9.1                             1.9.3.484-2ubuntu1.2                    amd64
igloonet/icinga-plugins