Fixed bug in Twig_Loader_Cakephp interface

Fixed bug in Twig_Loader_Cakephp interface that prevented multiple-template includes and fallback behaviors.

Twig_LoaderInterface defined: https://github.com/fabpot/Twig/blob/master/lib/Twig/LoaderInterface.php

Twig include "array of templates" defined: http://twig.sensiolabs.org/doc/tags/include.html

Signed-off-by: Lee Hilton <lee.hilton@hipstercreative.com>