Add uniqueids=never to ignore INITIAL_CONTACT notifies

With uniqueids=no the daemon still deletes any existing IKE_SA with the
same peer if an INITIAL_CONTACT notify is received.  With this new option
it also ignores these notifies.

src/starter/args.c

@@ -61,6 +61,7 @@ static const char *LST_unique[] = {
 	"yes",
 	"replace",
 	"keep",
+	"never",
 	 NULL
 };