Resolve "L'erreur de validation du montant des VPN ne donne pas la fourchette acceptable"
a demandé de fusionner 203-l-erreur-de-validation-du-montant-des-vpn-ne-donne-pas-la-fourchette-acceptable vers develop
Closes #203 (closed)
The function price_valid? in service_sale_template now raise an error in case of problem and true otherwise. should we prefix it with assert_ ?