supplier can view inventory

update the database to run
supplier can add item

missing GUI part
iteration 1 demo

supplier can add and modify items, supermarket can choose a supplier to
order from
Merge branch 'master' of https://github.com/truly-auto/SENG403

Conflicts:
	src/main/java/FoodLink/database.java
	src/main/java/FoodLink/gui/AddItem.java
	src/main/java/FoodLink/gui/SupplierSys.java