account: cash statement: onchange_journal_id changes the field last_closing_balance which is not in the bank statement view -> breaks YAML tests

observed in latest v7

In that on_change:

http://bazaar.launchpad.net/~openerp/openobject-addons/7.0/view/head:/account/account_cash_statement.py#L167

the field last_closing_balance is set. However, the view of the account.bank.statement (which is the same object indeed) does not have the field.

This breaks YAML tests, should someone dare to write one on the bank statement.

I suppose having that field invisible="1" in the bank statement view account.view_bank_statement_form would fix that.

Thanks!