Add the possibility for named parameters in requests

I received a mail with a feature request:

> I am trying to use your Backbone.rpc to connect my Backbone application to
> a JSON-RPC API. (Yes, I am working with a 'rusty old Java developer. 8-) I
> notice that when submitting and receiving data, the code uses positional
> parameters. Is there a simple way to get it to use named parameters
> instead? I have looked over the code and, frankly, some of it is over my
> head because I am relatively new to JavaScript and Backbone. After reading
> the docs, it wasn't clear to me how or whether this is even possible.