In CI 2.1.0, it appears the Security class has been added to the core

In CI 2.1.0, it appears the Security class has been added to the system/core folder and is loaded automatically as well.

Using $this->load->library('security'); in controllers currently returns FALSE, yet you might not notice because the Security class is already loaded.
I discovered this because of a custom Loader class I was using caused an error when loading the Security class in this controller.