v0.40.0

• all:
  • Update to protobuf-golang v1.3.1.
• datastore:
  • Attempt to decode GAE-encoded keys if initial decoding attempt fails.
  • Support integer time conversion.
• pubsub:
  • Add PublishSettings.BundlerByteLimit. If users receive pubsub.ErrOverflow,
    this value should be adjusted higher.
  • Use IPv6 compatible target in testutil.
• bigtable:
  • Fix Latin-1 regexp filters in bttest, allowing \C.
  • Expose PassAllFilter.
• profiler:
  • Add log messages for slow path in start.
  • Fix start to allow retry until success.
• firestore:
  • Add admin client.
• containeranalysis:
  • Add apiv1 client.
• grafeas:
  • Add apiv1 client.