A promise based JSON command shell

As part of the Waterken server, I've been providing a Javascript
library that implements promises. Recently, I've tried generalizing
the implementation so that it works with a wider variety of JSON
resources, while still supporting the promise-based API.

I've written up some documentation for the new implementation at:

http://waterken.sourceforge.net/web_send/

I'm looking for comments and criticism before posting this to a wider
audience, such as the JSON mailing list.

--Tyler