Add a very basic deploy script for mojo.

We could do something much more sophisticated for deploy in the future.

Also add #!mojo:sky_viewer to .sky file demos

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/885653006

examples/example-scrollable.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

examples/file-browser.sky

+#!mojo mojo:sky_viewer
 <!--
 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be

examples/flights-app/index.sky

+#!mojo mojo:sky_viewer
 <sky>
   <import src="flights-app.sky" as="FlightsAppElement"/>
   <style>

examples/fps-counter.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

examples/touch-demo.sky

+#!mojo mojo:sky_viewer
 <sky>
 <import src="fps-counter.sky" />
 <style>

examples/widgets/index.sky

+#!mojo mojo:sky_viewer
 <!--
 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be