Modified .gitignore file.
Modified the main Swing surface. Changed the 'Add Product' button to 'Add'. Setted the setMnemonic, setAccelerator, setToolTipText methods for each of the menu items.
Added the test class for the Contain class
Added the test class for the Manufacturer class
Added the test class for the Product class
Added the test class for the Warehouse class
Deleted proba.java file.