start commissioner candidate petition process

        Returns:
            True: successful to start commissioner candidate petition process
            False: fail to start commissioner candidate petition process

def allowCommission(self):
        """start commissioner candidate petition process

        Returns:
            True: successful to start commissioner candidate petition process
            False: fail to start commissioner candidate petition process
        """
        print '%s call allowCommission' % self.port
        try:
            cmd = WPANCTL_CMD + 'commissioner start'
            print cmd
            if self.isActiveCommissioner:
                return True
            if self.__sendCommand(cmd)[0] != 'Fail':
                self.isActiveCommissioner = True
                time.sleep(40) # time for petition process and at least one keep alive
                return True
            else:
                return False
        except Exception, e:
            ModuleHelper.WriteIntoDebugLogger('allowcommission() error: ' + str(e))