Public methods; add 'existsbyIsbn' method

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

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

@@ -8,7 +8,8 @@ import org.springframework.data.repository.CrudRepository;
 
 public interface BookRepository extends CrudRepository<Book, Long> {
 
-	// Handles both INSERT and UPDATE queries
-	List<Book> findById(String title);
+	public List<Book> findById(String title);
+
+	public boolean existsByIsbn(String isbn);
 
 }

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

@@ -8,6 +8,6 @@ import org.springframework.data.repository.CrudRepository;
 
 public interface CategoryRepository extends CrudRepository<Category, Long> {
 
-	List<Category> findByName(String name);
+	public List<Category> findByName(String name);
 
 }