Fixes Last N event duplicating another event, causing exception when used in the client app.

JitsiConferenceEvents.js

     /**
      * You are included / excluded in somebody's last N set
      */
-    IN_LAST_N_CHANGED: "conference.lastNEndpointsChanged",
+    IN_LAST_N_CHANGED: "conference.inLastNChanged",
     /**
      * A media track ( attached to the conference) mute status was changed.
      */

modules/RTC/DataChannels.js

             else if ("InLastNChangeEvent" === colibriClass) {
                 var oldValue = obj.oldValue;
                 var newValue = obj.newValue;
+
                 // Make sure that oldValue and newValue are of type boolean.
                 var type;