added tests around using objects as values in a query string

I was curious how request encoded:

```javascript
      request.get({
        url: 'http://' + host + ':' + port + '/user',
        json: true,
        qs: {
         where: { foo: 'bar' }
        }
      }, function (err, resp, body) {
        return done();
      });
```

And:

```javascript
      request.get({
        url: 'http://' + host + ':' + port + '/user',
        json: true,
        qs: {
         order: ['foo', 'bar']
        }
      }, function (err, resp, body) {
        return done();
      });
```

So I put some tests around it.