http browserify broken when sending a full node url object

```
var url = {
host: "localhost:8081",
hostname: "localhost",
href: "http://localhost:8081/api/foo?bar=baz",
method: "GET",
path: "/api/foo?bar=baz",
pathname: "/api/foo",
port: "8081",
protocol: "http:",
query: "bar=baz",
search: "?bar=baz",
slashes: true
};
var request = http.get(url, noop);
```

```
expected: "http://localhost:8081/api/foo?bar=baz"
actual: "http://localhost:8081:8081/api/foo?bar=baz"
```

The url that is requested has the port in it 2 times. This is because of this line.
https://github.com/substack/http-browserify/blob/master/index.js#L7

I am finishing up a pull request to fix this where it will try host first, then hostname+port.

Please let me know if you have any input.

Start at index.js line 7, where the request URL is assembled from the supplied Node URL object. Reproduce the example with http.get and verify that the generated URL is http://localhost:8081/api/foo?bar=baz, with the port included only once.

Written by the indexing model from the issue text.