Using pid as discriminator for mergeId

... for favourite and upvote notifications.

src/socket.io/helpers.js

@@ -80,7 +80,7 @@ SocketHelpers.sendNotificationToPostOwner = function(pid, fromuid, notification)
 				pid: pid,
 				nid: 'post:' + pid + ':uid:' + fromuid,
 				from: fromuid,
-				mergeId: notification + '|' + postData.tid,
+				mergeId: notification + '|' + pid,
 				topicTitle: results.topicTitle
 			}, function(err, notification) {
 				if (!err && notification) {

src/socket.io/posts/favourites.js

@@ -124,11 +124,11 @@ module.exports = function(SocketPosts) {
 
 			/*
 			hooks:
-				filter.post.upvote
-				filter.post.downvote
-				filter.post.unvote
-				filter.post.favourite
-				filter.post.unfavourite
+				filter:post.upvote
+				filter:post.downvote
+				filter:post.unvote
+				filter:post.favourite
+				filter:post.unfavourite
 			 */
 			plugins.fireHook('filter:post.' + command, {data: data, uid: socket.uid}, function(err, filteredData) {
 				if (err) {