ACL manager UI

This PR provides a fully working UI to create and update object's ACL.

The UI is only enabled if Sonata Admin is properly configured to use ACL.
The current user must have the `MASTER` right to edit permissions and only users with the `OWNER` right can edit `OWNER` and `MASTER` permissions.

English and French translations are provided.

This PR only provides an UI to set ACL. It does not include list filtering, show, edit and create access... I've some snippets for that. If somebody is interested, I can copy them here, but they are not ready for upstream inclusion. 

![capture decran 2013-07-23 a 09 55 39](https://f.cloud.github.com/assets/57224/840269/4f2addcc-f36d-11e2-8888-312621ab568f.png)