BigQuery

## wip.

### Docs: https://stephenplusplus.github.io/gcloud-node/#/docs/master/bigquery

Carrying on from #262. Just opening this so anyone interested can follow along.

Basically, I'm trying to explain if you don't pass a callback, you're asking for a readable stream. If you do provide a callback, you're going to be in charge of requesting more data if it exists.