Updated to Cloud SDK v0.9.30

Merging will re-generate the google/cloud-sdk docker image.

This update includes the latest Cloud SDK v0.9.30 and its sub-commands.  Minor update to the instructions based on if the user is running this image from outside of Compute Engine or within it.

@brendandburns - mind kicking the tires before I merge since @proppy is out-of-pocket?