Fixed Missing rest_enabled_logging check for response code logging

As noted here chriskacerguis#412 (comment)

Author: JCBuck

application/libraries/REST_Controller.php

@@ -500,7 +500,11 @@ public function response($data = NULL, $http_code = NULL, $continue = FALSE)
         }
 
         set_status_header($http_code);
-        $this->_log_response_code($http_code);
+        
+        // JC: Log response code only if rest logging enabled
+        if (config_item('rest_enable_logging')) {        
+            $this->_log_response_code($http_code);
+        }
 
         // If zlib.output_compression is enabled it will compress the output,
         // but it will not modify the content-length header to compensate for