fixed #121 where monsters and npcs can hold items

This commit fixes #121 so that monsters can hold items other than gold and xp. It works by adding another line in each monster's java file that calls AddRandomItems and passes in the playerlevel and a variable amount of itemIds. The function that randomly chooses one of the items and adds it into the monster's items. 

When you kill the monter or the npc, it drops the items and notifies you about the drop. In the future we may want to expand the amount of items that are randomly assigned to the monster based on the playerLevel but I figured for right now, one random item is more than enough especially considering the amount of monsters laying around the underground. 

I also fixed a bug where npcs where not being removed from the map when they were killed (i.e the Brotherhood Member).