namedQueries doesn't work with STI

I have a hierarchy with STI:

``` groovy
class Entity {
static namedQueries = {
notDeleted {
}
}

class ConcreteEntity extends Entity {
}
```

When I'm calling `ConcreteEntity.notDeleted.list()` it returns both `Entity` and `ConcreteEntity` instances, but when I'm calling `ConcreteEntity.findAllWhere(...)` it returns only `ConcreteEntity` instances as expected.

I did some investigation for this problem (Grails 2.5.1, grails-datastore-gorm-hibernate-core 3.1.5) and found it adds named query methods for `ConcreteEntity` twice. First time in right context (domainClass == ConcreteEntiy) when it collecting all `namedQueries` closures from current Entity and its hierarchy. Second time in wrong context (domainClass == ConcreteEntity), when collecting `classesToAugment` in HibernateNamedQueriesBuilder. It adds the domainClass itself and all sub classes (including `ConcreteEntity`). So it overwrites ConcreteEntity.notDeleted method with closure for `ConcreteEntity` with new closure for `Entity`.

I monkey patched with `metaClass` method from `HibernateNamedQueriesBuilder` and now it works as expected:

``` groovy
HibernateNamedQueriesBuilder.metaClass.getClassesToAugment = {
return [domainClass]
}
```

Start with HibernateNamedQueriesBuilder.getClassesToAugment and the named-query augmentation path described in the issue, using the Grails 2.5.1 and grails-datastore-gorm-hibernate-core 3.1.5 context. Reproduce the ConcreteEntity.notDeleted.list() behavior with STI and compare it with findAllWhere(...). Done means the named query returns only ConcreteEntity instances, without the monkey patch.

Written by the indexing model from the issue text.