Fixed adding/destroying individual nodes across all providers.
Disabled GCP Volumes. GCP TF provider doesn't support optional GCP volumes, any configuration not using a volume would fail. Waiting for hashicorp/terraform#7034 to land before re enabling.
Updated GCP/Azure/AWS firewall rules to follow Rancher 2.0 guidelines. (Should fix clusters not going green for these providers)
Sort provider image names in reverse chronological order.
Cleaned up create manager code in preparation of multi cloud manager support.
@fayazg