add license note to all live examples

[naomiblack]

All of our live examples (codepen, plunkr) must include the following statement at the end of each file:

Copyright 2016 Google Inc. All Rights Reserved.
Use of this source code is governed by an MIT-style license that can be found in the LICENSE file at http://angular.io/license

I have the license hosted on angular.io, but you could point to a more angularjs-specific hosted copy if you prefer. It doesn't matter -- the text for all our licenses is the same.

[petebacondarwin]

Fixed in angularjs.org by 4473f53

[petebacondarwin]

I guess we still need to do it for all the Plunkers from the angular.js docs app too? Or did someone do that already?

[petebacondarwin]

Closing and opening a new issue for this in angular.js project.