Go back to using uuids until URNs in certificates are more stable.

protogeni/lib/GeniCredential.pm.in

@@ -376,14 +376,14 @@ sub Sign($$)
 	return -1;
     }
     my $target_cert = $self->target_cert()->cert();
-    my $target_urn = $self->target_uri();
+    my $target_urn = $self->target_uuid();
 
     if (!defined($self->owner_cert())) {
 	print STDERR "No owner certificate attached to $self\n";
 	return -1;
     }
     my $owner_cert = $self->owner_cert()->cert();
-    my $owner_urn = $self->owner_uri();
+    my $owner_urn = $self->owner_uuid();
 
     # Credential expiration: hard-code to 24 hours from now.
     my @expt = gmtime( time() + 24 * 60 * 60 );