refactor(shadow_dom): remove ShadowDomStrategy in favor of @View(encapsulation)

BREAKING CHANGES:
- `ShadowDomStrategy` was removed. To specify the encapsulation of a component use `@View(encapsulation: ViewEncapsulation.NONE | ViewEncapsulation.EMULATED | ViewEncapsulation.NATIVE)`
- The default encapsulation strategy is now `ViewEncapsulation.EMULATED` if a component contains styles and `ViewEncapsulation.NONE` if it does not. Before this was always `NONE`.
- `ViewLoader` now returns the template as a string and the styles as a separate array

modules/angular2_material/src/components/button/button.ts

@@ -1,9 +1,12 @@
-import {Component, View, LifecycleEvent} from 'angular2/angular2';
+import {Component, View, LifecycleEvent, ViewEncapsulation} from 'angular2/angular2';
 import {isPresent} from 'angular2/src/facade/lang';
 
 
 @Component({selector: '[md-button]:not([href])'})
-@View({templateUrl: 'package:angular2_material/src/components/button/button.html'})
+@View({
+  templateUrl: 'package:angular2_material/src/components/button/button.html',
+  encapsulation: ViewEncapsulation.NONE
+})
 export class MdButton {
   // TODO(jelbourn): Ink ripples.
 }
@@ -15,7 +18,10 @@ export class MdButton {
   host: {'(click)': 'onClick($event)', '[tabIndex]': 'tabIndex'},
   lifecycle: [LifecycleEvent.onChange]
 })
-@View({templateUrl: 'package:angular2_material/src/components/button/button.html'})
+@View({
+  templateUrl: 'package:angular2_material/src/components/button/button.html',
+  encapsulation: ViewEncapsulation.NONE
+})
 export class MdAnchor {
   tabIndex: number;