added constants.php file and implemented constants for file system modes
diff --git a/system/codeigniter/Common.php b/system/codeigniter/Common.php
index d9ddf80..4554a71 100644
--- a/system/codeigniter/Common.php
+++ b/system/codeigniter/Common.php
@@ -52,7 +52,7 @@
 		}

 		

 		fclose($fp);

-		@chmod($file, 0777);

+		@chmod($file, DIR_WRITE_MODE);

 		@unlink($file);

 		return TRUE;

 	}