Issue 2948: fix "kubectl get events" result not sorted

Fixes #2948
* Added a "TIME" column to results from both "kubectl get events" and "kubectl describe pod x"
* Added code to sort the result from "kubectl get events" by event timestamp
  * Verified that sorting has negligible impact on runtime while sorting 8000 events
* Confirmed that "kubectl describe pod x" is already sorting results by time
* Added unit tests to verify both "kubectl get events" and "kubectl describe pod x" results are sorted by time.