Choices includes all of the available domain names in the system, as
well as any domains that are in ejabberd configuration.
Tests:
- Disable a domain. It is removed from ejabberd config.
- Enable a domain. It is added to ejabberd config.
- Enable all name services. Run ejabberd functional tests and observe
that they pass.
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>