gcppubsubdemo | teaching pub/sub using Go

In another terminal, execute the publisher with. And in another terminal, execute the subscriber with. The default for both the publish and subscribe commands are to publish and receive data continuously. Use Ctrl-C to stop execution noting that in this case, the subscription ID and topics will remain created in the pub/sub emulator. When using the --once option these will be removed upon exit. The --verbose option is particularly useful when learning how the code flows. It enables DEBUG and TRACE level logging useful for following the code logic.