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/libcharon/sa/ikev2/tasks/ike_auth.c

@@ -435,7 +435,8 @@ METHOD(task_t, build_i, status_t,
 		message->add_payload(message, (payload_t*)id_payload);
 
 		if (idr && message->get_message_id(message) == 1 &&
-			this->peer_cfg->get_unique_policy(this->peer_cfg) != UNIQUE_NO)
+			this->peer_cfg->get_unique_policy(this->peer_cfg) != UNIQUE_NO &&
+			this->peer_cfg->get_unique_policy(this->peer_cfg) != UNIQUE_NEVER)
 		{
 			host_t *host;