drive.files.get in 0.4.1 causes HTML 400 error

Given this code:

```
  client.drive.files.get({fileId:'root'})
  .withAuthClient(req.user.auth)
  .execute(function(err,rootFile){
    console.log( 'get root', err, rootFile );
  });
```

The "rootFile" parameter contains HTML content with error code 400 "Bad Request".
