update CHANGELOG

Author: eheydrick

CHANGELOG.md

@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed at [Keep A Changelog](http://keepachangelog.com/)
 
 ## [Unreleased]
+
+## [1.0.0] - 2016-12-27
 ### Fixed
 - metric-postgres-connections: Handle postgres version 9.6 and above.