Add support for namespace flag

[mandre]

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[openshift-ci-robot]

@mandre: The following test failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
ci/prow/e2e-openstack	040f87d	link	/test e2e-openstack

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[tomassedovic]

/lgtm

I've tested this with openshift/installer#1849 and the workers come up again.

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mandre, tomassedovic

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[trown]

/test e2e-openstack