REST API: do not expose/export book hashes

Signed-off-by: Pekka Helenius <fincer89@hotmail.com>

bookstore/src/main/java/com/fjordtek/bookstore/model/BookHashRepository.java

@@ -18,7 +18,7 @@ import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 @RepositoryRestResource(
 		path            = "bookhashes",
 		itemResourceRel = "bookhashes",
-		exported        = true
+		exported        = false
 		)
 public interface BookHashRepository extends CrudRepository<BookHash, String> {