Add typings for router exports.

Use `nativescript-angular/router` as the recommended entrypoint

Author: hdeshev

src/nativescript-angular/router.d.ts

@@ -0,0 +1,5 @@
+import {Type} from 'angular2/core';
+
+export var NS_ROUTER_PROVIDERS: any[];
+export var NS_ROUTER_DIRECTIVES: Type[];
+export var routerTraceCategory: string;

src/nativescript-angular/router.ts

@@ -0,0 +1,5 @@
+export {
+    NS_ROUTER_PROVIDERS,
+    NS_ROUTER_DIRECTIVES,
+    routerTraceCategory
+} from "./router/ns-router";