[JIRA] (OVIRT-2147) Add docker to OST requirements

Add docker to OST requirements ------------------------------ Key: OVIRT-2147 URL: https://ovirt-jira.atlassian.net/browse/OVIRT-2147 Project: oVirt - virtualization made easy Issue Type: Bug Components: OST Reporter: Gal Ben Haim Assignee: infra - Explain in the docs that docker is needed because of the UI tests. - Verify in run_suite that docker is available. We can use the "requirements" section in the suite's vars file that docker is needed (or implement more generic requirement).