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

tools/broccoli/html-replace/SCRIPTS.html

@@ -5,7 +5,6 @@
     baseURL: '/',
     packages: {
       'angular2_material': {defaultExtension: 'js'},
-      'upgrade': {defaultExtension: 'js'},
       'benchmarks': {defaultExtension: 'js'},
       'playground': {defaultExtension: 'js'},
       // TODO(rado): These helpers don't end up in the bundle, thus they should