feat(query): adds support for descendants and more list apis.

Additional clean up of query code.

Closes: #1935

BREAKING CHANGE:
By default Query only queries direct children.

modules/angular2/src/core/annotations_impl/annotations.ts

@@ -231,14 +231,13 @@ import {DEFAULT} from 'angular2/change_detection';
  *
  * ### Injecting a live collection of descendant directives
  *
- * Note: This is will be implemented in later release. ()
- *
- * Similar to `@Query` above, but also includes the children of the child elements.
+ * By passing the descendant flag to `@Query` above, we can include the children of the child
+ * elements.
  *
  * ```
  * @Directive({ selector: '[my-directive]' })
  * class MyDirective {
- *   constructor(@QueryDescendents(Dependency) dependencies:QueryList<Dependency>) {
+ *   constructor(@Query(Dependency, {descendants: true}) dependencies:QueryList<Dependency>) {
  *   }
  * }
  * ```

modules/angular2/src/core/annotations_impl/di.ts

@@ -1,5 +1,6 @@
-import {CONST, stringify} from 'angular2/src/facade/lang';
+import {CONST, stringify, isPresent} from 'angular2/src/facade/lang';
 import {DependencyAnnotation} from 'angular2/src/di/annotations_impl';
+import {resolveForwardRef} from 'angular2/di';
 
 /**
  * Specifies that a constant attribute value should be injected.
@@ -53,6 +54,13 @@ export class Attribute extends DependencyAnnotation {
  */
 @CONST()
 export class Query extends DependencyAnnotation {
-  constructor(public directive: any) { super(); }
+  descendants: boolean;
+  constructor(private _directive: any, {descendants = false}: {descendants?: boolean} = {}) {
+    super();
+    this.descendants = descendants;
+  }
+
+  get directive() { return resolveForwardRef(this._directive); }
+
   toString() { return `@Query(${stringify(this.directive)})`; }
 }