need a handler throttle

[richwolski]

woofc-container uses multiple threads to service the event log and (now) forks and execs each handler. If one handler does multiple puts, it is possible to create a backlog of processes within the container. Probably need a throttle that will restrict new process spawns when the backlog reaches a specified maximum. The easiest way to do this would be to add a global semaphore to woofc-container that the WooFForker() threads use to determine when it is safe to call fork()