[FIX] account: check for profit/loss accounts

in method `button_confirm_cash` of `account.cash.statement`

The check was verifying that the profit/loss account
was set on the journal, and if it was, it raised that it
wasn't, which is obviously wrong.

This was solved in Odoo 8.0 by replacing the code
by something more readable in 9dc9169, and the same
logic to check that the profit/loss accounts are
set is still there.

Closes odoo#2924

addons/account/account_cash_statement.py

@@ -296,7 +296,7 @@ def button_confirm_cash(self, cr, uid, ids, context=None):
                 continue
 
             for item_label, item_account in TABLES:
-                if getattr(obj.journal_id, item_account):
+                if not getattr(obj.journal_id, item_account):
                     raise osv.except_osv(_('Error!'),
                                          _('There is no %s Account on the journal %s.') % (item_label, obj.journal_id.name,))