[ci skip] Change some log messages' level

'Class Loaded' type of messages flood log files when
log_threshold is set to 2 (debug). They're now logged
as 'info' level.

This is manually applying PR #1528, which was created
to do the same thing, but became outdated.
diff --git a/system/libraries/Ftp.php b/system/libraries/Ftp.php
index f6279cf..4794d75 100644
--- a/system/libraries/Ftp.php
+++ b/system/libraries/Ftp.php
@@ -112,7 +112,7 @@
 	public function __construct($config = array())
 	{
 		empty($config) OR $this->initialize($config);
-		log_message('debug', 'FTP Class Initialized');
+		log_message('info', 'FTP Class Initialized');
 	}
 
 	// --------------------------------------------------------------------