PHPDoc: `CCacheDependency` → `CCacheDependency|ICacheDependency`

`CChainedCacheDependency` implements `ICacheDependency` interface, but does not extends `CCacheDependency`. But both `CDbConnection::cache()` and `CActiveRecord::cache()` methods could also accept `CChainedCacheDependency` besides `CDbCacheDependency`, etc.

This type specification imprecision leads IDEs to show warnings (at least PhpStorm warns about that).

Before this fix:
![](http://storage3.static.itmages.ru/i/13/0118/h_1358498886_3215627_78cbd44896.png)

After this fix:
![](http://storage4.static.itmages.ru/i/13/0118/h_1358498894_8901039_0213e7e089.png)