docs: create public API surface

Closes #1181

modules/angular2/src/directives/for.js

@@ -4,6 +4,9 @@ import {View} from 'angular2/src/core/compiler/view';
 import {isPresent, isBlank} from 'angular2/src/facade/lang';
 import {ListWrapper} from 'angular2/src/facade/collection';
 
+/**
+ * @publicModule angular2/directives
+ */
 @Viewport({
   selector: '[for][of]',
   bind: {

modules/angular2/src/directives/if.js

@@ -2,6 +2,9 @@ import {Viewport} from 'angular2/src/core/annotations/annotations';
 import {ViewContainer} from 'angular2/src/core/compiler/view_container';
 import {isBlank} from 'angular2/src/facade/lang';
 
+/**
+ * @publicModule angular2/directives
+ */
 @Viewport({
   selector: '[if]',
   bind: {

modules/angular2/src/directives/non_bindable.js

@@ -1,5 +1,8 @@
 import {Decorator} from 'angular2/src/core/annotations/annotations';
 
+/**
+ * @publicModule angular2/directives
+ */
 @Decorator({
   selector: '[non-bindable]',
   compileChildren: false

modules/angular2/src/directives/switch.js

@@ -29,6 +29,7 @@ import {Parent} from 'angular2/src/core/annotations/visibility';
  *   <template [switch-default]>...</template>
  * </ANY>
  * ```
+ * @publicModule angular2/directives
  */
 @Decorator({
   selector: '[switch]',
@@ -140,6 +141,8 @@ export class Switch {
  * // match against a constant string
  * <template [switch-when]="'stringValue'">...</template>
  * ```
+ *
+ * @publicModule angular2/directives
  */
 @Viewport({
   selector: '[switch-when]',
@@ -175,6 +178,8 @@ export class SwitchWhen {
  *
  * ```
  * <template [switch-default]>...</template>
+ *
+ * @publicModule angular2/directives
  * ```
  */
 @Viewport({