refactor(render): remove recursion from renderer

The goal is to make implementing a renderer straight forward.

BREAKING_CHANGE:

- Renderer interface was redone / simplified.
- `DirectDomRenderer` was replaced by `DomRenderer`.
- `DirectDomRenderer.setImperativeComponentRootNodes` is replaced
  by the following 2 steps:
    1. `ViewManager.getComponentView(elementRef) -> ViewRef`
    2. `DomRenderer.setComponentViewRootNodes(viewRef, rootNodes)`
- all `@View` annotations need to have a template, but the template
  may be empty. Previously views that had a `renderer` property did
  not have to have a `template`.
- `dynamicComponentLoader.loadIntoNewLocation` does no more allow
  to pass an element, but requires a css selector.
  Special syntax: `:document` can be used as prefix to search globally
  on the document instead of in the provided parent view.

Part of #1675

modules/angular2/angular2.js

@@ -5,4 +5,4 @@ export * from './directives';
 export * from './forms';
 export {Observable, EventEmitter} from 'angular2/src/facade/async';
 export * from 'angular2/src/render/api';
-export {DirectDomRenderer} from 'angular2/src/render/dom/direct_dom_renderer';
+export {DomRenderer, DOCUMENT_TOKEN} from 'angular2/src/render/dom/dom_renderer';