Also add relative_path to destination

Because the destination url does not include the relative_path

src/routes/authentication.js

@@ -110,8 +110,8 @@
 					require('../socket.io').emitUserCount();
 
 					plugins.fireHook('filter:register.complete', uid, req.body.referrer, function(err, uid, destination) {
-						if(destination) {
-							res.redirect(destination);
+						if (destination) {
+							res.redirect(nconf.get('relative_path') + destination);
 						} else {
 							res.redirect(nconf.get('relative_path') + '/');
 						}