Fix for valve with flow meter

• Add service set_flow_alarm_timer for valve with flow meter. This set a timer to stop flow alarm action for up to 24 hrs. Flow alarm action is automatically reactivated after the timer end.
• Fix service description for valve.
• Code reformat for services in valve.
• Fix code for valve service implementation.
• Add documentation for set_flow_alarm_timer.
• Fix flow meter water statistic.