Add documentation and scripts to help run simulations on GCP.

Dockerfile

docs/_book.yaml

docs/gcp_setup.md

docs/install.md

tensorflow_federated/proto/v0/BUILD

tensorflow_federated/python/simulation/server_utils.py

tensorflow_federated/python/simulation/worker.py

tensorflow_federated/tools/client/BUILD

tensorflow_federated/tools/client/Dockerfile

tensorflow_federated/tools/client/build_image.sh

tensorflow_federated/tools/client/publish_image.sh

tensorflow_federated/tools/client/test.py

tensorflow_federated/tools/development/BUILD

tensorflow_federated/tools/runtime/gcp/BUILD

tensorflow_federated/tools/runtime/gcp/Dockerfile

tensorflow_federated/tools/runtime/gcp/build_image.sh

tensorflow_federated/tools/runtime/gcp/deploy_endpoint.sh

tensorflow_federated/tools/runtime/gcp/publish_image.sh