adds failing test
- appears that timestamp queries emit a lot of `rows` with length == 0
- `self.once('end')` is added each of these times
- assertion on listener count shows that more than 10 listeners are applied
passes `stream-tester-timestamp`
- moves 'end' event listener to constructor, only listen once
- ensures all existing tests still green
Merge pull request #4 from tbuchok/master

maxListeners on timestamp queries