refactor(core): add Query.read and remove DynamicComponentLoader.loadIntoLocation.

This adds the feature for `@ViewChild`/`@ViewChildren`/`@ContentChild`/`@ContentChildren` to define what to read from the queried element.

E.g. `@ViewChild(`someVar`, read: ViewContainerRef)` will locate the element with a variable `someVar` on it and return a `ViewContainerRef` for it.

Background: With this change, Angular knows exactly at which elements there will be `ViewConainerRef`s as the user has to ask explicitly of them. This simplifies codegen and will make converting Angular templates into server side templates simpler as well.

BREAKING CHANGE:
- `DynamicComponentLoader.loadIntoLocation` has been removed. Use `@ViewChild(‘myVar’, read: ViewContainerRef)` to get hold of a `ViewContainerRef` at an element with variable `myVar`.
- `DynamicComponentLoader.loadNextToLocation` now takes a `ViewContainerRef` instead of an `ElementRef`.
- `AppViewManager` is renamed into `ViewUtils` and is a mere private utility service.

modules/angular2/test/router/integration/impl/fixture_components.ts

@@ -1,4 +1,4 @@
-import {Component, ComponentRef} from 'angular2/core';
+import {Component, ComponentRef, ViewContainerRef, ViewChild} from 'angular2/core';
 import {
   AsyncRoute,
   Route,
@@ -11,7 +11,6 @@ import {
 import {PromiseWrapper} from 'angular2/src/facade/async';
 import {isPresent} from 'angular2/src/facade/lang';
 import {DynamicComponentLoader} from 'angular2/src/core/linker/dynamic_component_loader';
-import {ElementRef} from 'angular2/src/core/linker/element_ref';
 
 @Component({selector: 'goodbye-cmp', template: `{{farewell}}`})
 export class GoodbyeCmp {
@@ -144,16 +143,17 @@ export class RedirectToParentCmp {
 @RouteConfig([new Route({path: '/', component: HelloCmp})])
 export class DynamicLoaderCmp {
   private _componentRef: ComponentRef = null;
-  constructor(private _dynamicComponentLoader: DynamicComponentLoader,
-              private _elementRef: ElementRef) {}
+  @ViewChild('viewport', {read: ViewContainerRef}) private _viewport: ViewContainerRef;
+
+  constructor(private _dynamicComponentLoader: DynamicComponentLoader) {}
 
   onSomeAction(): Promise<any> {
     if (isPresent(this._componentRef)) {
       this._componentRef.destroy();
       this._componentRef = null;
     }
-    return this._dynamicComponentLoader.loadIntoLocation(DynamicallyLoadedComponent,
-                                                         this._elementRef, 'viewport')
+    return this._dynamicComponentLoader.loadNextToLocation(DynamicallyLoadedComponent,
+                                                           this._viewport)
         .then((cmp) => { this._componentRef = cmp; });
   }
 }