add multi-role management and add missing roles

[GlennCavarle]

Summary

The Front has to be compliant with the permission management provided by the backend. First, missing roles (user, super admin) have to be added in the role list. Finally, the permissions of each role have to be merged to provide multi-role management.

[GlennCavarle]

Right now, an exception is thrown when a role does not exist. Maybe, we can be more "flexible" and just ignore undefined roles. What do you think ?

[PapsOu]

I think we must throw an exception if using an undefined role can produce an unexpected behavior. If dealing with a fake role does not expose sensitive features, we probably don't need to throw exception and failing silently (may be displaying a flash message, but the message itself won't be very clear for users)