[FIX] pos: increase delay between scale readings

The hw_scale module uses its own internal thread
for reading weights, independently of the polling
done by the POS screen.
The shortest internal reading interval is around
200ms, so polling every 50ms is useless.
150ms seems a good compromise in terms of perception
and resource use.

addons/point_of_sale/static/src/js/screens.js

@@ -280,7 +280,7 @@ var ScaleScreenWidget = ScreenWidget.extend({
             return self.pos.proxy.scale_read().then(function(weight){
                 self.set_weight(weight.weight);
             });
-        },{duration:50, repeat: true});
+        },{duration:150, repeat: true});
 
     },
     get_product: function(){