message: prepare changelog for v1.0
diff: @@ -6,8 +6,10 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
  and this project adheres to [Semantic Versioning](http://semver.org/).
  <!--## Unreleased-->
  -
  <!-- List New Changes Here -->
  +
  +## [1.0.0] - 2017-04-11
  +
  * [Breaking] Remove Node v4 support: Node v4 is no longer in Active LTS, so as per the [Polymer Tools Node.js Support Policy](https://www.polymer-project.org/2.0/docs/tools/node-support) polymer-build will not support Node v4. Please update to Node v6 or later to continue using the latest verisons of Polymer tooling.
  * New Feature: add automatic [HTTP/2 push manifest](https://github.com/GoogleChrome/http2-push-manifest) generation for HTTP/2 Push-enabled servers.
  