[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to do the same thing, but became outdated.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/core/Controller.php b/system/core/Controller.php
index 06005b0..4ad10fc 100644
--- a/system/core/Controller.php
+++ b/system/core/Controller.php
@@ -77,7 +77,7 @@
 
 		$this->load =& load_class('Loader', 'core');
 		$this->load->initialize();
-		log_message('debug', 'Controller Class Initialized');
+		log_message('info', 'Controller Class Initialized');
 	}
 
 	// --------------------------------------------------------------------