Created Class Ingredients.java which statically stores the
ingredientList and inventoryList. By storing IngredientList, we do not
have to query it from the server over and over, reducing network usage
on mobile plans, and increasing the speed at which the screen loads.
Storing the inventory allows the list to persist past the screen, and be
called from activities such as Browse Recipes.

Edited Fragment_Inventory.java to call the static ingredient lists
rather than the local copy it used to possess. Furthermore, items may
now be removed from the inventoryList.