[FIX]modal: when closing a modal, focus previous one to allow several escape hit key
[FIX] Kanban / Modal - Close the backdrop from dialog when we open the dialog for add a new column in kanban view. This bug was introduced since with use bootstrap modal
Forward-port of latest saas-4, up to revision 3994 (rev-id jke@openerp.com-20140509131203-4gy3nhlj0v6fk7zv)