[FIX] web: reload after wizard when record has been removed cause exception

If an action unlink the current records (e.g. unreconcile on account.move.reconcile), trigger history_back to avoid errors when trying to reload inexistant record (opw 607883)
This is a partial backport of saas-4 code (rev c0db6ae, 162ad1c) and should not be forward ported.
Merge branch '7.0' of https://github.com/odoo/odoo into 7.0-linux64