Creates new file for inventory demo

Demo2 was getting a little long in the tooth
As a result, we'll be using Demo3 from here
on out.
Gives methods/members to IventoryItem class
Uses ArrayList to create inventory

To address the possibility of a player owning
multiple items, an array was made in order 
to keep track of these items. Use array instead
of declaring multiple member items that may not 
be enough or may be too much. Here the Array 
expands to accommodate just as much data as is
needed.
implements interface for InvetoryItems

Get/Set/Add/Drop methods for manipulating
InventoryItems class
Merge branch 'master' of github.com:mkturner/java-quickstart

Cleaning up Repo