Add helpers to common.tls for creating TLS certificates for a CA,
server and client.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20181116155325.22428-6-berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: spelling and quoting touchups]
Signed-off-by: Eric Blake <eblake@redhat.com>