Only show quantity unit that are available on a resource, as it does not make sense to use a quantity unit that does not exists on the resource, because it won't be possible to convert this quantity  (like in erp5_trade)

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@24276 20353a03-c40f-0410-a6d1-a30d3c3de9de