(remove the tax_category key because the base_amount is the same for all the
tax_category).
- change base_amount_table name in base_amount_current_value_dict wich is a
  litle more clear


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@17767 20353a03-c40f-0410-a6d1-a30d3c3de9de