Update CHANGELOG.md

Author: Cylix

CHANGELOG.md

@@ -1,5 +1,20 @@
 # Changelog
 
+## [v3.1](https://github.com/Cylix/cpp_redis/releases/tag/3.1)
+### Changes
+* Fix: compilation for specific windows compilers concerning atomic variables
+* Fix: handle correctly array replies with negative size by returning a null reply instead of throwing an invalid format exception
+* Fix: Bump tacopie version to retrieve a fix concerning gethostbyname() thread-safety issue on unix
+* Fix: compilation for programs based on Qt ('slots' conflict) 
+
+### Additions
+* Add some overloads for the Z set functions to support floating point values
+* Add an auth method to the subscriber class to allow a subscriber to authenticate on the redis server
+
+### Removals
+None
+
+
 ## [v3.0](https://github.com/Cylix/cpp_redis/releases/tag/3.0)
 ### Changes
 * Rewrite the network side of cpp_redis by using the [tacopie library](https://github.com/Cylix/tacopie)