added countdown.rb example (jvd)
added countdown.rb example (jvd)

rogervaas/tropo-samples,tropo/tropo-samples,rsackler/tropo-samples,rsackler/tropo-samples,rsackler/tropo-samples,rogervaas/tropo-samples,tropo/tropo-samples,tropo/tropo-samples,rogervaas/tropo-samples,rogervaas/tropo-samples,tropo/tropo-samples,rsackler/tropo-samples