Address #161 comments.
  * Use Duration.sinceUtc instead of ad-hoc logic
  * Check the process has actually exited in tests
Improve /server/shutdown functionality

  * add forceShutdownOnError - don't shutdown by default if app errors on stop
  * add shutdownTimeout - timeout shutdown waiting for apps to stop
  * add requestTimeout - timeout http request waiting for shutdown
  * add delayForHttpReturn - how long to wait before System.exit to let the request complete gracefully
  * deprecate delayMillis and make it an alias for delayForHttpReturn

Update dependant effectors.
Make the task name visible in UI
Treat empty parameter fields as null values