Adds a second parameter named domain to muc_size module.

Adds and the default conference. part where the muc module live in default deployments.

resources/prosody-plugins/mod_muc_size.lua

 function handle_get_room_size(event)
 	local params = parse(event.request.url.query);
 	local room_name = params["room"];
-	local room = get_room_from_jid(room_name);
+	local domain_name = params["domain"];
+	local room_address = room_name .. "@" .. "conference." .. domain_name;
+	local room = get_room_from_jid(room_address);
 	local participant_count = 0;
 
-	log("debug", "Querying room %s", tostring(room_name));
+	log("debug", "Querying room %s", tostring(room_address));
 
 	if room then
 		local occupants = room._occupants;
 function handle_get_room (event)
 	local params = parse(event.request.url.query);
 	local room_name = params["room"];
-	local room = get_room_from_jid(room_name);
+	local domain_name = params["domain"];
+	local room_address = room_name .. "@" .. "conference." .. domain_name;
+	local room = get_room_from_jid(room_address);
 	local participant_count = 0;
 	local occupants_json = array();
 
-	log("debug", "Querying room %s", tostring(room_name));
+	log("debug", "Querying room %s", tostring(room_address));
 
 	if room then
 		local occupants = room._occupants;