fa23cdc caless tests: make debug log of certificates sensible

Authored and Committed by stlaz 6 years ago
    caless tests: make debug log of certificates sensible
    
    CA-less tests debug logging uses representation of a variable
    containing the certificate object, which does not help very much.
    Use the actual DER representation of the certificate on such places.
    
    Reviewed-By: Michal Reznik <mreznik@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>