hook doesn't continue if operation was a del

I now know why I'm getting repeated work on my app: it's because I'm deleting the record before calling done.
The  `doHook` function didn't check whether the operation was a del or a put, marking the job as pending.
The `doJob` was still running again and not triggering [this guard](https://github.com/dominictarr/level-trigger/blob/00e28039ac25c61501f09da7c1098edd3efd3c61/index.js#L42) because the repeated data still contained the previous `put` change.

Still, I'm not 100% sure about this change: Was there a reason why you wanted to repeat doJob if the job was deleted before it was complete?