Add sky-drawer to the framework

sky/examples/appish.sky

+#!mojo mojo:sky_viewer
+<!--
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+-->
+<sky>
+<import src="/sky/framework/sky-element/sky-element.sky" as="SkyElement" />
+<import src="example-scaffold.sky" />
+
+<sky-element name="example-app">
+<template>
+  <example-scaffold>
+    <div class="title">Awesome app</div>
+    <div class="menu">This is a menu</div>
+    <div class="body">This is an awesome app.</div>
+  </example-scrollable>
+</template>
+<script>
+module.exports = class extends SkyElement {
+}.register();
+</script>
+</sky-element>
+
+<example-app />
+</sky>