refactor(Lifecycle hooks): move the hooks to their own module (lifecycle_hooks)

BREAKING CHANGE

Lifecycle hooks now live in the `angular2/lifecycle_hooks` module.
They previously lived in the `metadata` module.

modules/angular2/test/core/compiler/dynamic_component_loader_spec.ts

@@ -20,7 +20,8 @@ import {
 
 import {Injector} from 'angular2/di';
 import {NgIf} from 'angular2/directives';
-import {Component, View, ViewMetadata, OnDestroy} from 'angular2/metadata';
+import {Component, View, ViewMetadata} from 'angular2/metadata';
+import {OnDestroy} from 'angular2/lifecycle_hooks';
 import {DynamicComponentLoader} from 'angular2/src/core/compiler/dynamic_component_loader';
 import {ElementRef} from 'angular2/src/core/compiler/element_ref';
 import {DOCUMENT} from 'angular2/src/core/render/render';

modules/angular2/test/core/compiler/element_injector_spec.ts

@@ -35,9 +35,9 @@ import {
   Query,
   ViewQuery,
   ComponentMetadata,
-  DirectiveMetadata,
-  OnDestroy
+  DirectiveMetadata
 } from 'angular2/metadata';
+import {OnDestroy} from 'angular2/lifecycle_hooks';
 import {bind, Injector, Binding, Optional, Inject, Injectable, Self, SkipSelf, InjectMetadata, Host, HostMetadata, SkipSelfMetadata} from 'angular2/di';
 import {ViewContainerRef} from 'angular2/src/core/compiler/view_container_ref';
 import {TemplateRef} from 'angular2/src/core/compiler/template_ref';

modules/angular2/test/core/directive_lifecycle_integration_spec.ts

@@ -13,11 +13,8 @@ import {
   TestComponentBuilder
 } from 'angular2/test_lib';
 
+import {Directive, Component, View, ViewMetadata} from 'angular2/metadata';
 import {
-  Directive,
-  Component,
-  View,
-  ViewMetadata,
   OnChanges,
   OnInit,
   DoCheck,
@@ -25,7 +22,7 @@ import {
   AfterContentChecked,
   AfterViewInit,
   AfterViewChecked
-} from 'angular2/metadata';
+} from 'angular2/lifecycle_hooks';
 
 export function main() {
   describe('directive lifecycle integration spec', () => {