7.0 : Add modules hr_expense_onchange and hr_expense_show_taxes

The module hr_expense_onchange is just a technical module that adds on_change on 2 fields of expense
lines : unit_amount and unit_quantity. It is designed to be used as a dependency for other modules, including hr_expense_show_taxes and l10n_fr_hr_expense_private_car.

The module hr_expense_show_taxes will allow you to see the untaxed amount and tax amount on
each expense line. You will also see the total untaxed and total taxes of the expense.