-add style to all the pages
-modify the look of the view "caisse"
-we have to filter the category by Jquery in order to keep the focus on
a button category when it has been clicked
-the button edit doesn't work anymore in product, I have to find why
-add the TVA as a model in our project
-develop a function to get the dummy reference to a product but I don't
see how to call it from listproduct.html