Parse totalRows to int.

It seems despite the docs[1] for getQueryResults stating that
totalRows returns an "unsigned long", in fact it returns a string.

Here's a snippet taken from the API explorer

```
"jobReference": {
  "projectId": "foo",
  "jobId": "job_RHAjGYT8d5P1JPGYL1mkZu4uK1X"
},
"totalRows": "1148",
```

[1]: https://developers.google.com/bigquery/docs/reference/v2/jobs/getQueryResults