* Making release for most packages.

Every package except those that have already been released
(`google-cloud-core`, `google-api-core`, `google-cloud-bigquery`):

- `google-cloud`
- `google-cloud-bigtable`
- `google-cloud-datastore`
- `google-cloud-dns`
- `google-cloud-error-reporting`
- `google-cloud-firestore`
- `google-cloud-language`
- `google-cloud-logging`
- `google-cloud-monitoring`
- `google-cloud-resource-manager`
- `google-cloud-runtimeconfig`
- `google-cloud-spanner`
- `google-cloud-speech`
- `google-cloud-storage`
- `google-cloud-trace`
- `google-cloud-translate`
- `google-cloud-videointelligence`
- `google-cloud-vision`

* Adding changelog files for each package.