Produce .d.ts files from our typescript compilation.

Deliver them into our npm module output so users can consume them directly.

Fixes #3082

typing_spec/basic_spec.ts

@@ -1,5 +1,3 @@
-///<reference path="../dist/docs/typings/angular2/angular2.d.ts"/>
-
 import {Component, bootstrap, View} from 'angular2/angular2'
 
 @Component({
@@ -15,4 +13,4 @@ class MyAppComponent {
   constructor() { this.name = 'Alice'; }
 }
 
-bootstrap(MyAppComponent);
+bootstrap(MyAppComponent);