message: Chore: update changelog.md for release.
diff: +## X.Y.Z (INSERT_DATE_HERE)
  +
  +#### Major Changes
  +- [Concrete Syntax Tree / Semantic Actions Visitor.](https://github.com/SAP/chevrotain/issues/381)
  +
  +#### Documentation
  +- [Runnable offline tutorial source code.](https://github.com/SAP/chevrotain/pull/410)
  +
  +#### Bug Fixes
  +- [Definitions: Chevrotain don't support literal string as Token PATTERN in TypeScript.](https://github.com/SAP/chevrotain/pull/448)
  +
  +
  +
  ## 0.27.3 (3-31-2017)
  #### Minor Changes
  