Kickstart should trace the children of its child for resource usage information

It would be useful for the resource usage tracing if Kickstart would trace all of its descendants and not just its immediate child. That way, if the job uses a shell script wrapper, then the total resource usage of the entire job is captured. The need is similar to getrusage with RUSAGE_CHILDREN. We would want, say, the I/O for the entire process tree, not just the process invoked by Kickstart.