Added an example for Cloud Pub/Sub.
A little fix for usage.
Added Ack call
Refactored based on the codereview.
* Refactored clientAndID
* Separate fields unrelated to reporting.
Refactoring with more flat structure.
Removed unused const.
Wording and Naming
Merge pull request #64 from tmatsuo/pubsub-example

Adding Cloud Pub/Sub example