[WIP] - Resolved #2 + Added missing use statments

First of all, notice this is a **work in progress**

As stated in #2, there is 2 sorts of "missing use"
* the statment is missing: we just have to add the correct statment
* the annotations from Doctrine, which are auto-loaded without need of ``use``

As far as I have investigated, this is not an ``AnnotationReader`` but a ``SimpleAnnotationReader`` which is used.

So, we need to add "every" missing statments. This will resolve the issue until we take a big review of our custom auto-loader...

Finaly, I've renamed ``Cache\DAO\Entity`` to ``Cache\DAO\CacheEntity`` because of ambiguous behaviors on ``@Entity`` annotation used in this class.
Be careful about it when you will rebase with master cause it changed.