Add @ContactModel

[smaugho]

Similar to issue #139, a @ContactModel can be added to make the interface (as well as queries) with the Contacts library.

It will add as well a default Contact model to the app which can be used, and a @UseContacts should be created to handle Permission requests and so on.

A @ContatField can also be created in order to permit to use the model with any other one.

@ContactModel
public void Contact {
    String name;
    String email;
    String phone;
}