moved all model classes to a dedicated 'model' package

...g/springframework/samples/petclinic/model/BaseEntity.java

.../springframework/samples/petclinic/model/NamedEntity.java

...va/org/springframework/samples/petclinic/model/Owner.java

...a/org/springframework/samples/petclinic/model/Person.java

...java/org/springframework/samples/petclinic/model/Pet.java

.../org/springframework/samples/petclinic/model/PetType.java

...rg/springframework/samples/petclinic/model/Specialty.java

...java/org/springframework/samples/petclinic/model/Vet.java

...ava/org/springframework/samples/petclinic/model/Vets.java

...va/org/springframework/samples/petclinic/model/Visit.java

...springframework/samples/petclinic/model/package-info.java

...amework/samples/petclinic/repository/OwnerRepository.java

...framework/samples/petclinic/repository/PetRepository.java

...framework/samples/petclinic/repository/VetRepository.java

...amework/samples/petclinic/repository/VisitRepository.java

...es/petclinic/repository/jdbc/JdbcOwnerRepositoryImpl.java

...gframework/samples/petclinic/repository/jdbc/JdbcPet.java

...ples/petclinic/repository/jdbc/JdbcPetRepositoryImpl.java

...ples/petclinic/repository/jdbc/JdbcVetRepositoryImpl.java

...es/petclinic/repository/jdbc/JdbcVisitRepositoryImpl.java