Add jam package.json

[jam](http://jamjs.org/) is an increasingly popular JS package manager, in the style of npm but for browser deliverables.

I've created a basic `package.json` filled out with details like the duel licensing etc., with jQuery as a dependency, and the right dependency loading for require.js (which jam provides).

This can be used for [publishing the package](http://jamjs.org/docs#Publishing), so it can be included with `jam install` or by other `package.json` defined jam packages.