add categorys
handle the stock when a bill is submitted (javanullpointerexception to
resolve but the stock is correctly updated in the debug)
Merge branch 'NewMaster' of https://github.com/lucho9/ProjAppliWeb.git
into NewMaster

Conflicts:
	ProjAppliWeb/src/main/java/m2/project/model/Category.java
	ProjAppliWeb/src/main/java/m2/project/model/Facture.java
Merge remote-tracking branch 'origin/Master2'

Conflicts:
	ProjAppliWeb/src/main/java/m2/project/Application.java