Implement ModelList for Models Lists

[smaugho]

The method getModelList_ can implement (and return) a custom List named ModelList. This is an abstract class that includes a method named save.

A @LocalDBModel will implement a custom ModelList, that will save every element in a Transaction, so it would be enough to call models.save(), where models is the list of injected Models, to save every element in a transaction.

With this can be implemented also a List Upload for the server model.