wendelin_inventory: fillCategoryList now returns nothing

@Tyagov, can you merge, please? 

/reviewed-on nexedi/wendelin!15

bt5/erp5_wendelin_inventory/ExtensionTemplateItem/portal_components/extension.erp5.PandasInventory.py

@@ -313,7 +313,7 @@ class CategoryProcessor(object):
     transaction.commit()
     if duplicate_category:
       print 'Duplication added to the array: %s' % total_duplication 
-    return array
+    return
   
   def _getCategoriesDf(self):
     '''