message: Updated CHANGELOG.md for the 1.4.0 release.
diff: # Changelog
  ## Unreleased
  +<!-- Add new, unreleased items here. -->
  +
  +## v1.4.0 [08-08-2017]
  - Upgraded to Polymer Build ^2.0.0 which uses Polymer Bundler ^3.0.0.
  - When no specific option is set for Bundler's `rewriteUrlsInTemplates` the CLI attempts to get the version of Polymer for the project using `bower`. When Polymer 2.x is discovered, `rewriteUrlsInTemplates` is defaulted to `false`. In case of Polymer 1.x or where version can not be identified, it defaults to `true`. Any user settings override these defaults.
  - Fix issue where negative `extraDependencies` globs were not working.
  - test: Add support for WCT `config-file` option.
  -<!-- Add new, unreleased items here. -->
  ## v1.3.1 [07-06-2017]
  - Fixed [issue #710](https://github.com/Polymer/polymer-cli/issues/710) where the es5 custom elements adapter would not be added when bundling.
  