[PLAT-5112] : specific class for specific commodity future/forward according to the underlying type
[PLAT-5113] : present value using discounting for future/forward commodity
[PLAT-5114] : sensitivities using algorythme differentiantion for future/forward commodity
[PLAT-5141] : create a CommoditySensitivity object
[PLAT-5142] : create a MultiCurrencyCommoditySensitivity  object