fix(angular2): remove angular2.ts module

Closes #5815
Closes #5844

BREAKING CHANGE:

`angular2/angular2` was removed. Use the correct import from one of the barrels. E.g. `angular2/core`, `angular2/platform/browser`,  `angular2/common`, …

Note: This only applies to JavaScript, Dart is not changed.

tools/broccoli/trees/node_tree.ts

@@ -124,7 +124,7 @@ module.exports = function makeNodeTree(projects, destinationPath) {
   // because of the duplicate definitions.
   // TODO(alexeagle): remove this when typescript releases a fix
   nodeTree = replace(nodeTree, {
-    files: ['angular2/core.d.ts', 'angular2/angular2.d.ts'],
+    files: ['angular2/core.d.ts'],
     patterns: [{match: /$/, replacement: 'import "./manual_typings/globals-es6.d.ts";\r\n'}]
   });