[google|compute] Changes to how auth works.

Attempts to allow users to pass in a Google API object so they can do
different types of auth.
An attempt at an example
[google|compute] Fix spelling errors in example
[google|compute] Use a valid image for v1 in example
Fix some bugs with GCE auth refactoring
Fixes some bugs found in GCE examples
Fix some last bugs in gettng new google_client abstraction working
Merge pull request #2763 from icco/new_auth

[google|compute] Allow for different auth types.