refactor(async): refactor EventEmitter

Refactor EventEmitter and Async Facade to match ES7 Observable semantics, properly use RxJS typedefs, make EventEmitter inherit from RxJS Subject. Closes #4149.

BREAKING CHANGE:
- consumers of EventEmitter no longer need to call .toRx()
- EventEmitter is now generic and requires a type - e.g. `EventEmitter<string>`
- EventEmitter and Observable now use the `.subscribe(generatorOrNext, error, complete)` method instead of `.observer(generator)`
- ObservableWrapper uses `callNext/callError/callComplete` instead of `callNext/callThrow/callReturn`

modules/angular2/src/router/location.ts

@@ -79,7 +79,7 @@ export const APP_BASE_HREF: OpaqueToken = CONST_EXPR(new OpaqueToken('appBaseHre
 @Injectable()
 export class Location {
   /** @internal */
-  _subject: EventEmitter = new EventEmitter();
+  _subject: EventEmitter<any> = new EventEmitter();
   /** @internal */
   _baseHref: string;
 

modules/angular2/src/router/router.ts

@@ -59,7 +59,7 @@ export class Router {
   private _auxRouters = new Map<string, Router>();
   private _childRouter: Router;
 
-  private _subject: EventEmitter = new EventEmitter();
+  private _subject: EventEmitter<any> = new EventEmitter();
 
 
   constructor(public registry: RouteRegistry, public parent: Router, public hostComponent: any) {}