Description:
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GCE hammer always selects f1-micro image type regardless of requested image type,

How Reproducible:
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Always

Steps:
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1. Provision a GCE host from a hammer with the image anything other than f1-micro type.

1. hammer host create --architecture-id 1 --build true --compute-attributes 'machine_type=n1-standard-2, network=default, associate_external_ip=true' --compute-resource-id 1 --domain-id 1 --image-id 1 --operatingsystem-id 1 --provision-method image --puppet-ca-proxy-id 1 --puppet-environment-id 1 --puppet-proxy-id 1 --root-password changeme --volume 'size_gb=13, size_gb=11' --location-id 2 --organization-id 1 --name gcePlus1

Actual Behavior:
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1. The GCE Host is provisioned but the image type in provisioned is f1-micro always.

Expected Behavior:
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1. The GCE host should be provisioned with the requested image type in the hammer command.