chore(ngUpgrade): Move into Angular2

This is moving ngUpgrade into the main repository per #4838.
The ngUpgrade is published from the main import consistent with
https://docs.google.com/document/d/1rbVTKTYLz6p2smQNYI8h4-QN-m2PS6F3iQIDmSzn0Ww/edit#heading=h.6cxvr9awtf5r
Closes #4931

modules/angular2/angular2.ts

@@ -2,3 +2,4 @@ export * from './core';
 export * from './profile';
 export * from './lifecycle_hooks';
 export * from './bootstrap';
+export * from './upgrade';