Bundle and Component for dynamic configuration

Initial PR for discussing the component/bundle for dynamic configuration.

At the present state, a simple Entity holds a `Configuration`, which is a simple *key/value* store. The configuration Entity looks like this:

```php
protected $namespace = "";
protected $parameter;
protected $value;
```

A default adapter for using such an entity with doctrine `ORM` or `ODM` is proposed.
A second adapter to work with in memory/NOSQL key-value engines (such as `Redis`) is under way and needs to be discussed (Like injecting a specific `Redis` service or a more generic cache, like the [LiipDoctrineCacheBundle](https://github.com/liip/LiipDoctrineCacheBundle)

Some things need to be polished (like role intrefaces)
Hmmm, maybe this format is not understood at all... what do you think? Even if it is larger than 80 columns, this format is something really strange and difficult to understand... :(