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/src/core/compiler/compiler.ts

@@ -307,7 +307,8 @@ export class Compiler {
       templateAbsUrl: templateAbsUrl, template: view.template,
       styleAbsUrls: styleAbsUrls,
       styles: view.styles,
-      directives: ListWrapper.map(directives, directiveBinding => directiveBinding.metadata)
+      directives: ListWrapper.map(directives, directiveBinding => directiveBinding.metadata),
+      encapsulation: view.encapsulation
     });
   }