Fixed repeated network select/unselect causing no messages

Fixed repeated network select/unselect causing no messages

This patch fixes Jira issue IOT-453.  Previously, selecting
and unselecting the network repeatedly would put the ipserver
into a state where it would no longer propogate messages.

Change-Id: I6698e72782682b3523404137a2cef5ee410586bb
Signed-off-by: jw1103.kim <jw1103.kim@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/964
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Erich Keane <erich.keane@intel.com>