Allow for the specification of amd deps to load

This allows for RequireJS's short form (http://requirejs.org/docs/api.html#cjsmodule) require to be used in wrapped
code and will allow for modules produced with browserify to use external
modules when loaded with AMD.

e.g.

```js
;(function (f) {
  // CommonJS
  //...
  // RequireJS
  } else if (typeof define === "function" && define.amd) {
    define(["underscore"], f);

  // <script>
  } else {
  //...
})(function () {
var _ = require('underscore');
//...
});
```

This lays the foundation to address https://github.com/substack/node-browserify/issues/670 and https://github.com/substack/node-browserify/issues/801