The DNP3 smart-grid standard uses certificate with the IEC 62351-8
IECUserRoles extension. Add a profile for DNP3 certificates which
copies the IECUserRoles extension from the CSR, if present.
Also update cert-request to accept CSRs containing this extension.
Fixes: https://fedorahosted.org/freeipa/ticket/4752
Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>
