[WIP] Implement support for secondary index reads

Is it ok if I move this new request to the .then() callback in _get
So I will go something like https://gist.github.com/hardikj/f591f796c48ddb443ba8

Also, Is there any way to stop streaming in middle
see my comment here https://gist.github.com/hardikj/f591f796c48ddb443ba8#file-gistfile1-txt-L30