ItemRules

Added exception catch to entity damage being done with invalid materials. Most likely from using outdated plugins. At least this should stop beefing about it :)

* Will not work with mcMMO builds pre #1.4.0
* Even if you can't craft an item, you can use the item in crafting. e.g. you may restrict leather boots from being crafted, but if a player has leather boots, they can dye them.