fix(examples): prefix directives with Ng

modules/examples/src/forms/index.es6

@@ -1,4 +1,4 @@
-import {bootstrap, If, For, EventEmitter} from 'angular2/angular2';
+import {bootstrap, NgIf, NgFor, EventEmitter} from 'angular2/angular2';
 import {FormBuilder, Validators, formDirectives, ControlGroup} from 'angular2/forms';
 
 // TODO(radokirov): Once the application is transpiled by TS instead of Traceur,
@@ -42,7 +42,7 @@ import {View} from 'angular2/src/core/annotations_impl/view';
         </div>
       </div>
   `,
-  directives: [formDirectives, If]
+  directives: [formDirectives, NgIf]
 })
 class HeaderFields {
   header:ControlGroup;
@@ -144,7 +144,7 @@ class SurveyQuestion {
       <button (click)="submitForm()">Submit</button>
     </div>
   `,
-  directives: [formDirectives, For, HeaderFields, SurveyQuestion]
+  directives: [formDirectives, NgFor, HeaderFields, SurveyQuestion]
 })
 class SurveyBuilder {
   form:ControlGroup;

modules/examples/src/material/button/demo_app.html

@@ -74,7 +74,7 @@
 </section>
 
 
-<p template="for #item of items">
+<p template="ng-for #item of items">
   Repeated button:
   <button md-button tabindex="-1" (^click)="increment()">{{action}}</button>
   {{clickCount}}

modules/examples/src/material/button/index.js

@@ -1,4 +1,4 @@
-import {bootstrap, MapWrapper, ListWrapper, For} from 'angular2/angular2';
+import {bootstrap, MapWrapper, ListWrapper, NgFor} from 'angular2/angular2';
 import {MdButton, MdAnchor} from 'angular2_material/src/components/button/button'
 import {UrlResolver} from 'angular2/src/services/url_resolver';
 import {commonDemoSetup, DemoUrlResolver} from '../demo_common';
@@ -14,7 +14,7 @@ import {View} from 'angular2/src/core/annotations_impl/view';
 })
 @View({
   templateUrl: './demo_app.html',
-  directives: [MdButton, MdAnchor, For]
+  directives: [MdButton, MdAnchor, NgFor]
 })
 class DemoApp {
   previousClick: string;

modules/examples/src/todo/index.js

@@ -1,4 +1,4 @@
-import {bootstrap, For} from 'angular2/angular2';
+import {bootstrap, NgFor} from 'angular2/angular2';
 import {Store, Todo, TodoFactory} from './services/TodoStore';
 import {reflector} from 'angular2/src/reflection/reflection';
 import {ReflectionCapabilities} from 'angular2/src/reflection/reflection_capabilities';
@@ -17,7 +17,7 @@ import {View} from 'angular2/src/core/annotations_impl/view';
 })
 @View({
   templateUrl: 'todo.html',
-  directives: [For]
+  directives: [NgFor]
 })
 class TodoApp {
   todoStore: Store;