[IMP] payment, website_sale: better control of sale order confirmation in ecommerce.

Auto confirmation is now controlled by a field on the acquirer
that proposes to confirm
- at payment (Pay Now button on ecommerce)
- at payment confirmation (transaction feedback)
- never

Also fixed the state of tx for transfer transactions that was modified
for debugging in a previous task but not reverted.
Merge branch 'master' of https://github.com/odoo/odoo into master-linux64