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/test/router/integration/lifecycle_hook_spec.ts

@@ -51,7 +51,7 @@ import {DirectiveResolver} from 'angular2/src/core/linker/directive_resolver';
 
 var cmpInstanceCount;
 var log: string[];
-var eventBus: EventEmitter;
+var eventBus: EventEmitter<any>;
 var completer: PromiseCompleter<any>;
 
 export function main() {