More utilities to get ports in DropwizardConnectors

[sleberknight]

Add new methods to DropwizardConnectors that make it easy to get port information for application, admin, or all connectors.

These methods can assume (and therefore require) that the ServerFactory be a io.dropwizard.core.server.DefaultServerFactory. This restriction should be documented.

Users should be able to supply an io.dropwizard.core.Configuration or a io.dropwizard.core.server.DefaultServerFactory, which implies method overloads.

Methods that accept a Configuration should be designed such that we could change the implementation to handle both DefaultServerFactory and io.dropwizard.core.server.SimpleServerFactory it it ever becomes necessary. In that case, we could add more methods that mirror the existing ones, but which accept SimpleServerFactory and always return Port instances that have org.kiwiproject.registry.model.PortType of APPLICATION (since SimpleServerFactory only permits a single application port). The methods accepting Configuration could then be refactored to delegate to the appropriate methods based on the ServerFactory type.