Make port numbers protected (now static)

[jimisola]

I'm trying to contribute to Arconia and noticed that the port number in the different Container classes are private.

E.g. for RabbitMQContainer

private static final int DEFAULT_AMQP_PORT = 5672;

private static final int DEFAULT_AMQPS_PORT = 5671;

private static final int DEFAULT_HTTPS_PORT = 15671;

private static final int DEFAULT_HTTP_PORT = 15672;

This causes some duplication of code when such as class is extended and the subclass has the add those constants again.

Would it be possible to be a bit more lenient with the access and change it to protected?