refactor: export core APIs from angular2/core

This change moves many APIs to the angular2/core export.

This change also automatically adds FORM_BINDINGS in
the application root injector.

BREAKING CHANGE:
    Many dependencies that were previously exported from specific
    APIs are now exported from angular2/core. Affected exports, which
    should now be included from angular2/core include:

    angular2/forms
    angular2/di
    angular2/directives
    angular2/change_detection
    angular2/bootstrap (except for dart users)
    angular2/render
    angular2/metadata
    angular2/debug
    angular2/pipes
Closes #3977

modules/angular2/angular2.ts

@@ -1,18 +1,4 @@
-/**
- * The `angular2` is the single place to import all of the individual types.
- */
-
-// TODO(someone familiar with systemjs): the exports below are copied from
-// angular2_exports.ts. Re-exporting from angular2_exports.ts causes systemjs
-// to resolve imports very very very slowly. See also a similar notice in
-// bootstrap.ts
-export * from './metadata';
-export * from './change_detection';
 export * from './core';
-export * from './di';
-export * from './directives';
-export * from './forms';
-export * from './render';
 export * from './profile';
-export {bootstrap} from 'angular2/src/core/application';
 export * from './lifecycle_hooks';
+export * from './bootstrap';