Allow slow service startup again.

Allow slow service startup again.

Previously we enforced a maximum delay in reporting to the service
manager that the service was started, and waited for the application to
become unthrottled in the background.

Users may prefer that the service not report a started state until the
application is unthrottled.  Therefore we now loop and increment the
status checkpoint and wait hint to satisfy the service manager that we
aren't hung.

Thanks Tom Saul.