[IMP] http move db dispatching on the orm level

[IMP] http move db dispatching on the orm level
Split low level dispatching and high level dispatching.
Low level dispatching is used when the db is unknown it's only used by a few
controller in base and web.
High level dispatching is used when the db is known, it is used by most
controllers and it handles authentication and errors. Because it's a regular
osv object all it is fully overridable by openerp modules.

bzr revid: al@openerp.com-20131110014609-io03vspj2q1wtqa0