2016-12-21 Version 0.12.18 (Maintenance) Release

Notable changes:

* npm: upgrade from v2.15.1 to v2.15.11, including accurate updated
  license (Jeremiah Senkpiel)
* process: `process.versions.ares` now outputs the c-ares version (Johan
  Bergström)

PR-URL: https://github.com/nodejs/node/pull/10352