Respond with redir when directory requests are received without trailing slash

HTTP Directory requests without a trailing slash would "work" (the directory
listing would be sent), but the links to files, since they're relative to the
current request location, would be incorrect (missing the directory's virtual
subdir). So send a 301 response if a client requets a directory without a
trailing slash.

exec/webfileindex.ssjs

@@ -114,6 +114,11 @@ function root_index()
 }	
 
 if(http_request.dir !== undefined) {
+	if(http_request.virtual_path[http_request.virtual_path.length - 1] != '/') {
+		http_reply.status = "301 Moved";
+		http_reply.header.Location = http_request.virtual_path + '/';
+		exit();
+	}
 	dir_index(http_request.dir);
 } else if (http_request.lib !== undefined) {
 	lib_index(http_request.lib);