[Documentation Issue] Reference manual lacks the spec of Pub/Sub Message class

[miyakawataku]

Page Name: index
Release: 0.8.0

The reference manual lacks the specification of Pub/Sub Message class.

http://googlecloudplatform.github.io/gcloud-python/stable/pubsub-usage.html

[tseaver]

Thanks for the report! I will look into this issue today.

[dhermes]

Resolved in #1211