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/test/core/render/dom/compiler/style_inliner_spec.ts

@@ -19,7 +19,7 @@ import {Map, MapWrapper} from 'angular2/src/core/facade/collection';
 
 import {XHR} from 'angular2/src/core/render/xhr';
 
-import {bind} from 'angular2/di';
+import {bind} from 'angular2/core';
 
 export function main() {
   describe('StyleInliner', () => {

modules/angular2/test/core/render/dom/dom_testbed.ts

@@ -1,4 +1,4 @@
-import {Inject, Injectable} from 'angular2/di';
+import {Inject, Injectable} from 'angular2/core';
 import {isPresent} from 'angular2/src/core/facade/lang';
 import {MapWrapper, ListWrapper, Map} from 'angular2/src/core/facade/collection';
 import {PromiseWrapper, Promise} from 'angular2/src/core/facade/async';