Environment details

• OS: Ubuntu, OS X
• Node.js version: 8
• npm version: 6.0.1
• @google-cloud/bigquery version: 1.3.0

Steps to reproduce

1. Use createQueryStream to run a query with a very large payload, in the GB range of results.
2. Put a log in the data event handler for the stream.
3. Watch the memory usage of that Node process swell before even a single data event. (If you have a big enough query, you'll get an OOM error. e.g.:

OOM in node_modules/@google-cloud/common/src/util.js:185
 183   if (is.string(body)) {
 184     try {
>185       parsedHttpRespBody.body = JSON.parse(body);
 186     } catch (err) {
 187       parsedHttpRespBody.err = new util.ApiError('Cannot parse JSON response');
debug>

Can we get it to stream data as it gets it and NOT pool it up in memory?