Errata list should require either repo_id or repo info

@bbuckingham  discovered that you could do `katello errata list --org=ACME --content_view=NoSQL` although it didn't work properly. However, the errata description says that it lists errata for a repo. Moreover, the package command that mirrors this requires repo info. Lastly, many of the commands don't work (such as `katello errata list --org=ACME --product_label=Mongo`) unless you specify repo info. I also talked to Garik and he confirmed that errata list is meant to list the errata for a single repo.