Fix #2963

Changed all file permissions settings throught the framework
and the documentation.

Also added configuration settings for CI_Log and CI_Image_lib
diff --git a/system/database/DB_cache.php b/system/database/DB_cache.php
index b855ff2..2efb42c 100644
--- a/system/database/DB_cache.php
+++ b/system/database/DB_cache.php
@@ -156,14 +156,9 @@
 		$dir_path = $this->db->cachedir.$segment_one.'+'.$segment_two.'/';
 		$filename = md5($sql);
 
-		if ( ! is_dir($dir_path))
+		if ( ! is_dir($dir_path) && ! @mkdir($dir_path, 0750))
 		{
-			if ( ! @mkdir($dir_path, 0777))
-			{
-				return FALSE;
-			}
-
-			@chmod($dir_path, 0777);
+			return FALSE;
 		}
 
 		if (write_file($dir_path.$filename, serialize($object)) === FALSE)
@@ -171,7 +166,7 @@
 			return FALSE;
 		}
 
-		@chmod($dir_path.$filename, 0666);
+		chmod($dir_path.$filename, 0640);
 		return TRUE;
 	}