chore: rename modules/examples to modules/playground

The directory contains code authored in a style that makes it transpilable to dart. As such, these are not idiomatic examples of Angular 2 usage.

The main purpose of this directory is to enable experimentation with Angular within the angular/angular repository.

Closes #4342

Closes #4639

modules/playground/src/routing/index.ts

@@ -0,0 +1,13 @@
+import {InboxApp} from './inbox-app';
+import {bind, provide} from 'angular2/angular2';
+import {bootstrap} from 'angular2/bootstrap';
+import {ROUTER_PROVIDERS, HashLocationStrategy, LocationStrategy} from 'angular2/router';
+
+import {reflector} from 'angular2/src/core/reflection/reflection';
+import {ReflectionCapabilities} from 'angular2/src/core/reflection/reflection_capabilities';
+
+export function main() {
+  reflector.reflectionCapabilities = new ReflectionCapabilities();
+  bootstrap(InboxApp,
+            [ROUTER_PROVIDERS, provide(LocationStrategy, {useClass: HashLocationStrategy})]);
+}