copy events from existing instance
copy events from existing instance

otherwise we produce flapping alerts like

```
2017-11-02 04:08:01     ALERT_ENTITY_STARTED
"entity-name-H4Sh01[aws:1234567890:eu-central-1]"
{"td":3.89E-4,"worker":"plocal.ip-172-31-132-123","ts":1.50959207725566E9,"value":[{"Code":"instance-stop","Description":"The instance is running on degraded
hardware","NotBefore":"2017-11-14T22:00:00+00:00"}]}
2017-11-02 04:18:00     ALERT_ENTITY_ENDED
"entity-name-H4Sh01[aws:1234567890:eu-central-1]"
{"td":6.02E-4,"worker":"plocal.ip-172-31-132-123","ts":1.509592677890665E9,"value":[]}
2017-11-02 08:06:59     ALERT_ENTITY_STARTED
"entity-name-H4Sh01[aws:1234567890:eu-central-1]"
{"td":4.84E-4,"worker":"plocal.ip-172-31-140-110","ts":1.509606418656158E9,"value":[{"Code":"instance-stop","Description":"The instance is running on degraded
hardware","NotBefore":"2017-11-14T22:00:00+00:00"}]}
2017-11-02 08:16:59     ALERT_ENTITY_ENDED
"entity-name-H4Sh01[aws:1234567890:eu-central-1]"
{"td":5.74E-4,"worker":"plocal.ip-172-31-140-110","ts":1.50960701801336E9,"value":[]}
```

zalando/zmon-aws-agent,zalando/zmon-aws-agent