pubsub-0.30.0
Also: - Making a release of the umbrella package (since `google-cloud-pubsub` has transition from `0.29.x` to `0.30.x`) - Updating version with `.dev1` suffix in `bigquery_datatransfer`, `container` and `trace` packages - Adding `google-cloud-bigquery-datatransfer` and `google-cloud-container` to umbrella package