fix re-connection error: no retry mqtt conn. due to uncaught exception.
let close event triggred by try /cat to disconnect()
TODO: more elaboration required.
[2013-11-19 15:19:17.445] [WARN] MQTT - MH.waitCloseTimer out : try disconnect
[2013-11-19 15:19:17.461] [ERROR] Main - [uncaughtException] Error: CryptoStre is not writable
    at CleartextStream.CryptoStream.write (tls.js:259:11)
    at Connection.eval [as disconnect] (eval at <anonymous> (/home/daliworks/ving/src/device/node_modules/mqtt/lib/connection.js:1:0))
    at MqttClient._cleanUp (/home/daliworks/ving/src/device/node_modules/mqtt/lib/client.js:443:13)
    at MqttClient.destroy (/home/daliworks/ving/src/device/node_modules/mqtt/lib/client.js:382:10)
    at Object._onTimeout (/home/daliworks/ving/src/device/mqttHelper.js:142:19)
    at Timer.list.ontimeout (timers.js:101:19)
[2013-11-19 15:19:20.004] [INFO] Main - m28-000003a7f590 => 27.062