ws: Add a couple more login related messages/debug output

Closes #595
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
Signed-off-by: Marius Vollmer <marius.vollmer@redhat.com>
 * Adapt check-login.
ws: Add some more debug output for /ssh-transport/bad-problem test

Trying to solve this here:
https://travis-ci.org/cockpit-project/cockpit/jobs/25688198

Closes #597
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>