feat(debug): replace DebugElement with new Debug DOM

Now, using `ng.probe(element)` in the browser console returns
a DebugElement when in dev mode.

`ComponentFixture#debugElement` also returns a new DebugElement.

Breaking Change:

This is a breaking change for unit tests. The API for the DebugElement
has changed. Now, there is a DebugElement or DebugNode for every node
in the DOM, not only nodes with an ElementRef. `componentViewChildren` is
removed, and `childNodes` is a list of ElementNodes corresponding to every
child in the DOM. `query` no longer takes a scope parameter, since
the entire rendered DOM is included in the `childNodes`.

Before:

```
componentFixture.debugElement.componentViewChildren[0];
```

After
```
// Depending on the DOM structure of your component, the
// index may have changed or the first component child
// may be a sub-child.
componentFixture.debugElement.children[0];
```

Before:

```
debugElement.query(By.css('div'), Scope.all());
```

After:

```
debugElement.query(By.css('div'));
```

Before:

```
componentFixture.debugElement.elementRef;
```

After:

```
componentFixture.elementRef;
```

modules/angular2/src/core/render/api.ts

@@ -1,10 +1,16 @@
 import {ViewEncapsulation} from 'angular2/src/core/metadata/view';
+import {Injector} from 'angular2/src/core/di/injector';
 
 export class RenderComponentType {
   constructor(public id: string, public encapsulation: ViewEncapsulation,
               public styles: Array<string | any[]>) {}
 }
 
+export class RenderDebugInfo {
+  constructor(public injector: Injector, public component: any, public providerTokens: any[],
+              public locals: Map<string, any>) {}
+}
+
 export interface ParentRenderer { renderComponent(componentType: RenderComponentType): Renderer; }
 
 export abstract class Renderer implements ParentRenderer {
@@ -42,6 +48,8 @@ export abstract class Renderer implements ParentRenderer {
    */
   abstract setBindingDebugInfo(renderElement: any, propertyName: string, propertyValue: string);
 
+  abstract setElementDebugInfo(renderElement: any, info: RenderDebugInfo);
+
   abstract setElementClass(renderElement: any, className: string, isAdd: boolean);
 
   abstract setElementStyle(renderElement: any, styleName: string, styleValue: string);