Update changelog, bumping v2.7.0

Author: hollodotme

CHANGELOG.md

@@ -3,11 +3,11 @@
 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).
 
-## [2.7.0] - YYYY-MM-DD
+## [2.7.0] - 2019-04-28
 
 ### Added
 
-* Re-using of idle sockets - [#33]
+* Re-using of idle sockets for successive requests - [#33]
 
 ## [2.6.0] - 2019-04-02