Fix Jira Difect IOT-505

Fix Jira Difect IOT-505

MQTT-Fan plugin can't recognize mqtt broker server status.
so linux sample application cannot print connection error message
and try to turn on/off the fan
I modify plugin codes to check the connection status.

Change-Id: Id1eff1b4439bf1d473dd8a0873a187b721a4d93e
Signed-off-by: YounghyunJoo <yh_.joo@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/850
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Madan Lanka <lanka.madan@samsung.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>