p11tool: re-use ID from corresponding objects when writing certificates

That is when writing a certificate which has a corresponding public key, or private key in the token, ensure that we use the same ID for the objects. That eases the work of someone writing objects to certificates, and does not require him to manually detect the object IDs.

Resolves #160 (closed)

Signed-off-by: Nikos Mavrogiannopoulos nmav@redhat.com