fixed places where site_title was being referenced in config, instead of the correct "title"

src/socket.io/admin.js

@@ -176,7 +176,7 @@ SocketAdmin.email.test = function(socket, data, callback) {
 	if (plugins.hasListeners('action:email.send')) {
 		emailer.send('test', socket.uid, {
 			subject: '[NodeBB] Test Email',
-			site_title: meta.config.site_title || 'NodeBB'
+			site_title: meta.config.title || 'NodeBB'
 		});
 		callback();
 	} else {