Initial commits - Item Files

The Item class is a Java object representation of a single entry in the Item database table, similar to the Hero class/table. It is rather empty at the moment, but the idea is the same. Likewise the ItemHelper class is used to fill the item database table, and to retrieve information from it. A major difference from the HeroHelper is that items are fairly static. Once they are created their attributes do not change. The ItemHelper has the ability to add items to the database table from information in a JSON file. Right now this is limited to a base set of items in a hardcoded, internal JSON file, but in time the ability to add items from a chosen, external file will be added. base_game_items.json is the internal file that the ItemHelper is currently able to load.