Release Pub/Sub 0.32.0

* Updated Subscriber implementation
  * Revised shutdown mechanics
    * Fixes stop and wait! would hanging indefinitely.
    * Reduce the number of GRPC warnings printed.
  * Added error callbacks to the API
    *  Use error handler to be notified when unhandled errors
       occur on a subscriber's stream thread.
* Documentation updates.

Release Firestore 0.23.0

* Add Firestore Watch
  * A document reference or a collection reference/query can now be
    listened to for changes.
  * The following methods were added:
    * DocumentReference#listen
    * Query#listen
  * The following classes were added:
    * DocumentSnapshot
    * DocumentChange
    * DocumentListener
    * QuerySnapshot
    * QueryListener
* Support DocumentSnapshot objects as cursors.
* Fix mapping of geo Hash to GeoPoint resource.
* Query#select is no longer additive, it now replaces any previously
  selected fields.
* Documentation updates.

Release google-cloud-bigtable 0.1.0

* Initial release

Release google-cloud 0.56.0

* Add Cloud Bigtable
* Add Cloud Text-to-Speech API

Release Pub/Sub 0.31.1

* Fix bug in AsyncUnaryPusher,
  * The modify_ack_deadline requests were malformed.

Release google-cloud-os_login 0.2.0 with support for v1 of the API

Release BigQuery DataTransfer v0.2.0

Release google-cloud-vision v0.30.0

* Add async_batch_annotate_files method to Google::Cloud::Vision::Project

Release google-cloud-dlp 0.5.0

* Documentation update
* Credentials env_vars change

Release google-cloud-text_to_speech 0.1.0