All errors are also returned as json responses, following the structure described in Cornice.
If the '''service_entry''' field is not provided, it means that the node to use is the token server URL itself.
This is useful for single box set ups.
XXX need to document this in Cornice
* 406 : unacceptable - the client asked for an Accept we don't support (7)
* 503 : service unavailable (ldap or snode backends may be down) (8)
= Proposed Design =