SONATA-397 - Update administration menu by adding new "Administration" g...

...roup

I've updated configuration to give a new `Administration` menu with the following elements as follow:

![capture decran 2014-01-24 a 14 10 53](https://f.cloud.github.com/assets/103900/1994919/9c51db5a-84f9-11e3-8cbb-6a85f45dd534.png)