update test to the new amount generator way,

- categories contribution_share and salary_range are no longer 
necessary as variation is now done on the base_amount category
- defined getBaseAmountQuantity script to manage slice cases



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@41992 20353a03-c40f-0410-a6d1-a30d3c3de9de