Katello docker migrations

If you are running Katello from master, after the next time you pull, make sure you update your foreman_docker gem to 1.0.0 before you run your db migrations. You should be able to migrate up if you have no docker data. If you have docker data, it'll be dropped due to a new foreman_docker migration that drops docker_images and docker_tags.

If you hit any errors during the migration, ping me.