[BUGFIX] lose of roles by changing locale

lose of roles by changing locale => patch action:

__Tasks:__

- [x] gather feedback for my changes


__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| Tests pass?   | yes
| Fixed tickets | https://github.com/sulu-cmf/SuluSecurityBundle/issues/62
| Doc           | none