(gnutls_certificate_details): Return the public key fingerprint

* gnutls.c (gnutls_certificate_details): Also return the public
key fingerprint.
(Fgnutls_peer_status): Don't return the certificate fingerprint.
NSM: Use the public key hash as the fingerprint

* net/nsm.el (nsm-fingerprint): New function.
(nsm-fingerprint-ok-p): Use the public key hash as the fingerprint
instead of the certificate fingerprint.
NSM exception handling on changed certificates

* net/nsm.el (nsm-fingerprint): New function.
(nsm-fingerprint-ok-p): Use the public key hash as the fingerprint
instead of the certificate fingerprint.
(nsm-fingerprint-ok-p): If the fingerprint changed, then remove
previously accepted warnings.