TestXHTML: install a localization business template

To reveal invalid html in erp5_web's language selector
Only take products into account in stock tab on deliveries

We don't show stocks of services
Do not display stock tab on open sale orders.

Because they are not delivery and the implementation would have to be different
erp5_web: generate valid html

<u> tag does not exist in the standard used by erp5_web; use something which
should be equivalent
Business template format change

due to fc05b33b1281193b48d06c6ffd0858359734ec4e