Update CacheManager.php

when use cache as the redis driver,and I want to set the redis to link the cache connection ,but it does't work as I want.then I edit the CacheManager.php to support it.
'redis' => array(

		'cluster' => false,

		'default' => array(
			'host'     => 192.168.1.120',
			'port'     => 6379,
			'database' => 0,
		),
		
		'cache' => array(
			'host'     => '192.168.1.120',
			'port'     => 6379,
			'database' => 1,
		),

		'session' => array(
			'host'     => '192.168.1.120',
			'port'     => 6379,
			'database' => 2,
		),