Cannot pass options to the http module

[pogotc]

While using this module I ran into this issue: nodejs/node#7931 which can be fixed by passing family: 4 to the request object.

As far as I can tell there's no way to directly pass parameters to the underlying request object, or is there? I think this would be a useful feature to have.

[pogotc]

I've created a pull request for this: #139, args now accepts a new parameter request_option that accepts any options that should be passed down to the request function.