Client Presence Support and $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.