Initial commits - MainActivity Files

The main activity acts as a starting point for the app. Its interface consists of a list of existing heroes in the database with said list being defined in the HeroList class. It also serves as the parent activity to the hero creation and deletion dialogs and passes
events between them and the hero list. The final purpose of the main activity is to trigger the loading of a JSON file with item data into the item database table when that table is initially empty.