Merge pull request #147 from php-http/patch-changelog

Added changelog for 1.9.0

Author: dbu

CHANGELOG.md

@@ -1,6 +1,12 @@
 # Change Log
 
-## 1.9.0 - [unreleased]
+## 1.9.0 - 2019-01-03
+
+### Added
+
+- Support for PSR-18 clients
+- Added traits `VersionBridgePlugin` and `VersionBridgeClient` to help plugins and clients to support both
+  1.x and 2.x version of `php-http/client-common` and `php-http/httplug`.
 
 ### Changed