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/debug/debug_element_spec.ts

@@ -11,25 +11,21 @@ import {
   beforeEachBindings,
   it,
   xit,
-  TestComponentBuilder,
-  By,
-  Scope
+  TestComponentBuilder
 } from 'angular2/test_lib';
 
 import {DOM} from 'angular2/src/core/dom/dom_adapter';
 
-import {ListWrapper} from 'angular2/src/core/facade/collection';
 import {PromiseWrapper, EventEmitter, ObservableWrapper} from 'angular2/src/core/facade/async';
 
-import {Injectable} from 'angular2/di';
+import {Injectable, NgFor} from 'angular2/core';
+import {By, Scope} from 'angular2/src/core/debug';
 
 import {
   Directive,
   Component,
   View,
-} from 'angular2/metadata';
-
-import {NgFor} from 'angular2/src/core/directives/ng_for';
+} from 'angular2/src/core/metadata';
 
 @Injectable()
 class Logger {

modules/angular2/test/core/debug/debug_element_view_listener_spec.ts

@@ -12,18 +12,11 @@ import {
   it,
   xit,
   TestComponentBuilder,
-  By,
-  Scope,
-  inspectNativeElement
 } from 'angular2/test_lib';
 import {global} from 'angular2/src/core/facade/lang';
 import {APP_VIEW_POOL_CAPACITY} from 'angular2/src/core/compiler/view_pool';
-import {Injectable, bind} from 'angular2/di';
-import {
-  Directive,
-  Component,
-  View,
-} from 'angular2/metadata';
+import {bind, Component, Directive, Injectable, View} from 'angular2/core';
+import {inspectNativeElement} from 'angular2/src/core/debug';
 import {IS_DART} from '../../platform';
 
 @Component({selector: 'my-comp'})