CAS-1335: Disallow and reject empty service registry configurations

The `DefaultServicesManagerImpl` returns an instance of `RegisteredServiceImpl` that is friendly to all, when no service definitions are specified and the consumed list is empty.

```java
if (c.isEmpty()) {
            return this.disabledRegisteredService;
}
```

Disallow this behavior and lock down the service registry configuration to at least one definition. Authentication should fail when no services are defined, when this feature is activated.

https://issues.jasig.org/browse/CAS-1335