Add release date, bumping v2.7.2

Author: hollodotme

CHANGELOG.md

@@ -3,7 +3,7 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/) and [Keep a CHANGELOG](http://keepachangelog.com).
 
-## [2.7.2] - YYYY-MM-DD
+## [2.7.2] - 2019-05-31
 
 ### Improved