autoload credentials fails on google

[Curtis Hovey]

As seen at
    http://juju-ci.vapour.ws/view/Juju%20Revisions/job/functional-autoload-credentials-gce/9/console

The test fails. It has never worked since the test was changed to attempt a bootstrap. A likely reason is a value pass by the test or adde to config is wrong. The gce provider create a url from the information. We see a 404 because a bad url was constructed from bad information.

15:45:47 ERROR cmd supercommand.go:458 googleapi: got HTTP response code 404 with body: Not Found
15:45:47 DEBUG cmd supercommand.go:459 (error details: [{github.com/juju/juju/cmd/juju/commands/bootstrap.go:668: } {github.com/juju/juju/environs/bootstrap/prepare.go:99: } {github.com/juju/juju/environs/bootstrap/prepare.go:163: } {github.com/juju/juju/provider/gce/environ.go:172: } {github.com/juju/juju/provider/gce/google/conn.go:122: } {github.com/juju/juju/provider/gce/google/raw.go:47: } {googleapi: got HTTP response code 404 with body: Not Found}])
2016-10-18 15:45:47 ERROR Command '('juju', '--debug', 'bootstrap', '--constraints', 'mem=2G', 'google/us-east1', 'functional-autoload-credentials-gce', '--config', '/tmp/tmpPdgYdk.yaml', '--default-model', 'functional-autoload-credentials-gce', '--agent-version', '2.0.1', '--bootstrap-series', 'xenial', '--credential', 'testing-user')' returned non-zero exit status 1