feat(router): add support for using classes as guard

modules/@angular/router/src/interfaces.ts

@@ -0,0 +1,16 @@
+import {Observable} from 'rxjs/Observable';
+import {ActivatedRouteSnapshot, RouterStateSnapshot} from './router_state';
+
+/**
+ * An interface a class can implement to be a guard deciding if a route can be activated.
+ */
+export interface CanActivate {
+  canActivate(route:ActivatedRouteSnapshot, state:RouterStateSnapshot):Observable<boolean> | boolean;
+}
+
+/**
+ * An interface a class can implement to be a guard deciding if a route can be deactivated.
+ */
+export interface CanDeactivate<T> {
+  canDeactivate(component:T, route:ActivatedRouteSnapshot, state:RouterStateSnapshot):Observable<boolean> | boolean;
+}