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/router.ts

@@ -33,7 +33,7 @@ import {RouteRegistry} from './src/router/route_registry';
 import {Pipeline} from './src/router/pipeline';
 import {Location} from './src/router/location';
 import {APP_COMPONENT} from './src/core/application_tokens';
-import {Binding} from './di';
+import {Binding} from './core';
 import {CONST_EXPR} from './src/core/facade/lang';
 
 export const ROUTER_DIRECTIVES: any[] = CONST_EXPR([RouterOutlet, RouterLink]);