0.8.1-alpha 版本

发布日期: 2015-05-28

Client [Presence](https://github.com/emqtt/emqttd/wiki/Presence) Support and [$SYS Topics](https://github.com/emqtt/emqttd/wiki/$SYS-Topics) Redesigned!

Bugfix: issue #138 - when client disconnected normally, broker will not publish disconnected $SYS message

Bugfix: fix websocket url in emqttd/priv/www/websocket.html

Improve: etc/emqttd.config to allow websocket connections from any hosts

Improve: rel/reltool.config to exclude unnecessary apps.