[FEATURE REQUEST]: Percent or hard number for inventory notifications

[Pugglewuggle]

Right now there is a hard number for inventory notifications. However, for some items that are used often, it would be good to have a notification sent when the number is less than, say, 20% of the specified amount for an item instead of for a hard number. For example, if we normally stock 5 of an item it would be good to not get emails when we use one. But it would be good to get emails when we are down to 2. The other issue is that the threshold is the same for all items, which may have very different normal inventory quantities. Only 2 remaining may be okay for some items but would be an emergency if only 2 of another item are remaining.