Add not() as a junction expression (like and() and or()) to the query criteria API

[rbygrave]

So not() allows us to join multiple expression together that are wrapped in a NOT like:

    List<Customer> customers = Ebean.find(Customer.class)
        .where()
          .not()
            .gt("id", 1)
            .eq("anniversary", onAfter)
        .orderBy().asc("name")
        .findList();

Or in the nested case like:

    List<Customer> customers = Ebean.find(Customer.class)
        .where()
        .or()
          .eq("status", Customer.Status.ACTIVE)
          .not()
            .gt("id", 1)
            .eq("anniversary", onAfter)
          .endJunction() // end the not - optional in this case as it is the last one
        .orderBy().asc("name")
        .findList();

This also means that and(), or(), not() ... parallel the text search junctions of must(), should() and mustNot().