Update CHANGELOG.md and RELEASE_NOTES.md for 9.3.4 release

CHANGELOG.md

@@ -3,7 +3,7 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
-## [Unreleased]
+## [9.3.4] - 2019-10-21
 ### Fixed
 - Be compatible with all in-use cppzmq versions ([#530][pr-530], [#561][pr-561], [#273][i-273], [#499][i-499], [#535][i-535])
 
@@ -177,6 +177,7 @@ where a client application might show out of date/incorrect values.
 - CPU load when device has large number of attributes ([#404][pr-404]) 
 - push event performance issue ([#244][i-244])
 
+[9.3.4]: https://github.com/tango-controls/cppTango/compare/9.3.3...9.3.4
 [9.3.3]: https://github.com/tango-controls/cppTango/compare/9.3.2...9.3.3
 [9.3.2]: https://github.com/tango-controls/cppTango/compare/9.3.1...9.3.2
 [9.3.1]: https://github.com/tango-controls/cppTango/compare/9.3.0...9.3.1

RELEASE_NOTES.md

@@ -1,3 +1,13 @@
+# Tango C++ library 9.3.4 Release Notes
+October 21, 2019
+
+cppTango can now be built even with the zmq.hpp file provided by your favourite Linux distribution.
+
+Please refer to [CHANGELOG.md](https://github.com/tango-controls/cppTango/blob/9.3-backports/CHANGELOG.md) 
+for a detailed list of changes and references to corresponding Github issues and pull requests.
+
+You can see the source code comparison with Tango 9.3.3, as well as the commits and contributors on this page:
+https://github.com/tango-controls/cppTango/compare/9.3.3...9.3.4
 
 # Tango C++ library 9.3.3 Release Notes
 March 29, 2019