Support classifiers on install and deploy

The current api doesn't allow the use of classifiers in `pomegranate.aether/install` or `pomegranate.aether/deploy`.

To allow this, I propose adding a `:jar-files` keyword argument, that takes a map from classifier keyword to jar file path or `File`.  The `nil` classifier would be used for the unclassified jar.

The `:jar-file` argument would be maintained for simple uses cases and for backward compatibility.