chef-init should remove zombie processes

[jochenseeber]

Sometimes a service that is started by chef-init leaks child processes, creating zombie processes. When the service process ends, these processes are "pushed up" to the chef-init process.

This is of course a bug in the service process, however it happens quite often. For this reason, the normal system "init" process reaps these zombie processes and it would be great if chef-init would do the same.