added guest info to TechnicalAuthorizationTokenModel
return a 401 instead of a 403 in case of an oauth auth error as per http://tools.ietf.org/html/rfc6749 5.2
the partners registration endpoint needs to be open (it is secured by requiring the app secret in the url (needs to be exposed over SSL of course)
can't rely on the AuthHelper's getGuestId() at this point of course and automatic Jackson serialisation seems to be problematic (again)