fix(core): export LifeCycle at top-level modules

LifeCycle can now be imported via angular2/angular2 or
angular2/core, so that end users can inject it without
having to use the full source path.

Closes #3395

modules/angular2/change_detection.ts

@@ -15,6 +15,8 @@ export {
   ExpressionChangedAfterItHasBeenCheckedException,
   ChangeDetectionError,
 
+  ChangeDetector,
+  Locals,
   ChangeDetectorRef,
 
   WrappedValue,