Though the power control event tests passed, this step failed for me:
```
  File "/home/semyers/ve/cfme-qe/cfme_tests/fixtures/events.py", line 191, in check_all_expectations
    came = self.check_db(*params, after=preceeding_event, before=check_started)
  File "/home/semyers/ve/cfme-qe/cfme_tests/fixtures/events.py", line 153, in check_db
    assert len(data) > 0
TypeError: object of type 'instancemethod' has no len()
```

As a result, `self.stop()` was never called. In addition to dealing with the traceback above, it would be good to wrap this all in a try/finally block to ensure that `self.stop()` is called no matter what happens in here.