Made sure to instrument the old mapper as well as the new mapper
Don't bother logging the job conf when the trace is started
Added a method to state machine to allow outsider callers to join up to
the previous state machine context.  This allows asynchronous observers,
such as people getting status reports, to hook up to the partial state
of the state machine.
Added instrumentation to the Job client to join up with the
XTraceContext of a job when the job is complete
Make sure to join any parent processes for all times that system.exit is
called
Don't stringify exceptions, it breaks XTrace