changes to fluent-plugin-google-cloud to attach Kubernetes metadata to
logs.
Along with this, separate logs from containers in the cluster out from
logs from the daemons running on the node by instantiating two instances
of the output plugin, one which uses the new metadata (for containers)
and one which doesn't (for things like docker and the kubelet).
1. Move fluentd-gcp to be a core cluster addon, rather than a contrib.
2. Get rid of the synthetic logger under contrib, since the exact same
synthetic logger was also included in the logging-demo.
3. Move the logging-demo to examples, since it's effectively an example.
We should also consider adding on a GCP section to the logging-demo
example :)