Pulp

The current changeset interface takes a single repo version like:

    def __init__(self, importer, repo_version, additions=(), removals=()):
        """ 
        Args:
            importer (pulpcore.plugin.models.Importer): An importer.
            repo_version (pulpcore.plugin.models.RepositoryVersion): The new version to which
                content should be added and removed

The sync interface takes both an old_version and a new_version. We should think about if we want to have these interfaces be dissimilar or not.

We have mostly avoided unnecessary abbreviations in pulp 3. Suggest we use repository_version instead of repo_version. Please!