Fix potential memory leaks on realtime client disconnect not clean up server properly

Author: jackycute

lib/realtime.js

@@ -478,6 +478,7 @@ function disconnect(socket) {
             if (note.server.isDirty) {
                 updateNote(note, function (err, _note) {
                     if (err) return logger.error('disconnect note failed: ' + err);
+                    delete note.server;
                     delete notes[noteId];
                     if (config.debug) {
                         //logger.info(notes);
@@ -487,6 +488,7 @@ function disconnect(socket) {
                     }
                 });
             } else {
+                delete note.server;
                 delete notes[noteId];
             }
         }