Generalise aether/install and deploy

Enables install and deploy to transfer multiple files, not just a single jar and
pom file.

Adds an :artifact-map option to pomegranate.aether/install and
pomegranate.aether/deploy, taking a map from partial coordinate to file path.

Removes the :artifacts keyword argument from deploy-artifacts and install-artifacts.
Merge pull request #52 from hugoduncan/feature/deploy-install-classifiers

Support classifiers on install and deploy