release template files to public domain

[mykmelez]

We should release the template files to the public domain, so web developers who use them to bootstrap an app can choose their own license for the app. In some cases, this will require replacing template code that we obtained from other sources (like the GitHub Pages generator). The headers for files in the public domain are at the bottom of this page: https://www.mozilla.org/en-US/MPL/headers/.