Added the Google Cloud SDK part.

Cloud SDK allows users of the Google Cloud Platform to
easily manage Compute Engine, Cloud Storage, Bigquery
and App Engine from a simple CLI interface.

This part disables usage reporting, and users can optin
for this after installation.
Makes google-cloud-sdk/bin part of PATH.

This allows more tools installed with gcloud, such
as the dev_appserver.py from pkg-go, to be available
to the user.