Indeed, but it helped me realize that this PR will not work for all adapters, only for those where the "internal engine" (like Memcached) implements the TTL functionnality

Exemple of a non-working adapter : [Memory](https://github.com/zendframework/zf2/blob/master/library/Zend/Cache/Storage/Adapter/Memory.php#L313)
The TTL is **checked at read time**, and so the TTL value will be back to its original value. :cry: 

This PR is a better than nothing one, but we must be aware of this limitation.

Thoughts ?