EPP session handling fails

[vohmar]

After the last update we have a lot of session related issued in production

sessions getting mixed up - registrar gets authorization error for renew - in the logs we see that system thinks it's another registrar

we also see a lot of authorization errors with api-public marked as a user - registrar did not log out (info, poll and check queries)

[artur-intech]

#700 Includes a countermeasure

[vohmar]

#699 fixed the session mixup problem, also have not spotted mysterious loss of sessions any more - all api-public requests seem to be caused by unauthenticated users that have not logged in.