Configuration has been updated so the IDP requests
also pass through an Authorization component.
A new config option was added to choose
which authorization scheme to use for the IDP.
Account settings are stored using the WebID as key.
Reason for using the WebID is that this allows faster access to the settings
in authenticated requests.
A consequence of this is that passwords are now always required during registration,
and that there can only be 1 account per WebID.
The IDP behaviour has been changed to move all error related knowledge
to the IdentityProviderHttpHandler instead of managing it
in the Interactionhandlers.