Update stats views.

def update_views(self):
        """Update stats views."""
        # Call the father's method
        super(Plugin, self).update_views()

        # Add specifics informations
        # Alert and log
        for key in ['user', 'system', 'iowait']:
            if key in self.stats:
                self.views[key]['decoration'] = self.get_alert_log(self.stats[key], header=key)
        # Alert only
        for key in ['steal', 'total']:
            if key in self.stats:
                self.views[key]['decoration'] = self.get_alert(self.stats[key], header=key)
        # Alert only but depend on Core number
        for key in ['ctx_switches']:
            if key in self.stats:
                self.views[key]['decoration'] = self.get_alert(self.stats[key], maximum=100 * self.stats['cpucore'], header=key)
        # Optional
        for key in ['nice', 'irq', 'iowait', 'steal', 'ctx_switches', 'interrupts', 'soft_interrupts', 'syscalls']:
            if key in self.stats:
                self.views[key]['optional'] = True