Add typing for bind() which is also needed for demo

angular2/angular2.d.ts

@@ -602,4 +602,21 @@ declare module "angular2/angular2" {
    *
    */
  function Switch(): void;
-}
+}
+
+declare module "angular2/di" {
+  /**
+   * Provides an API for imperatively constructing {@link Binding}s.
+   *
+   * This is only relevant for JavaScript. See {@link BindingBuilder}.
+   *
+   * ## Example
+   *
+   * ```javascript
+   * bind(MyInterface).toClass(MyClass)
+   *
+   * ```
+   *
+   */
+   function bind(token: any): any;
+}