[Fix bug 1030694] Fix new metrics handling on event clone.

* When cloning new events without actual outcome, metric gets cloned.
* When cloning past events with actual outcome, metrics get cloned with outcome NULL.
* When cloning events with has_new_metrics=False, cloned event gets tagged as has_new_metrics=True
* Fix statsd counter for events clone
Merge pull request #787 from johngian/fix-1030694-metrics-clone

Fix new metrics handling on event clone.