Hack to improve compatibility with TypeScript

I've added small hack to improve compatibility with TypeScript.

Currently TypeScript doesn't allow to yield results of AMD modules, but putting all result to exports variable. So it is a bit hard to implement widgets this way.

e.g. if you write this widget:
``` js
import widget = module('durandal/widget');

export class widgetA {
    connstructor(element, settings) {
    }

    public methodA() {
    }
}
``` 

It will compiles to:
``` js
define(["require", "exports"], function(require, exports) {
    
    var widgetA = (function () {
        function widgetA() { }
        widgetA.prototype.connstructor = function (element, settings) {
        };
        widgetA.prototype.methodA = function () {
        };
        return widgetA;
    })();
    exports.widgetA = widgetA;    
})
```

And will never works as a Widget.

But with this hack you should just add this lines:
``` js
declare var exports;
exports.model = widgetA;
```
which compiles to:
``` js
exports.widgetA = widgetA;    
exports.model = widgetA;
```

And now it works fine. I hope TypeScript team will fix this in next releases of compiler, but for now I have no another idea how to avoid this limitation and work best way with Durandal and TypeScript.