add a new findAll which takes only the Specification and return a List

I want to be able to return a **List** of my entity, So I think a method like the following one must be added.

```java
     @NoRepositoryBean
     public interface JpaSpecificationExecutorWithProjection<T> {
         List<T> findAll(Specification<T> spec, Class<R> projectionClass);
     }
```