Replace deprecated GoogleCredential with new lib
This PR also introduced a CredentialsBundle class to carry
HttpTransport and JsonFactory object which are needed by
most of the GCP library to instantiate client.
The check for environment cannot be done when the task is defined,
otherwise running any task will fail when the check does not pass.
Instead, check the environment when the task executes.
I'm seeing odd errors in versions of Karma more recent than 3.0.0. While
I investiage, I'd like to see what Github has to say about these
dependencies (we got some vulnerability messages for earlier versions)
