show timestamp on system messages

public/language/en-GB/modules.json

@@ -62,9 +62,9 @@
 	"chat.owner": "Room Owner",
 	"chat.grant-rescind-ownership": "Grant/Rescind Ownership",
 
-	"chat.system.user-join": "%1 has joined the room",
-	"chat.system.user-leave": "%1 has left the room",
-	"chat.system.room-rename": "%2 has renamed this room: %1",
+	"chat.system.user-join": "%1 has joined the room <span class=\"timeago\" title=\"%2\"></span>",
+	"chat.system.user-leave": "%1 has left the room <span class=\"timeago\" title=\"%2\"></span>",
+	"chat.system.room-rename": "%2 has renamed this room to \"%1\" <span class=\"timeago\" title=\"%3\"></span>",
 
 	"composer.compose": "Compose",
 	"composer.show_preview": "Show Preview",