oo-diagnostics: add test_sshd_permit_root_login

Add test_sshd_permit_root_login for node hosts to verify that root logins
are permitted in order to facilitate moving gears using oo-admin-move.

This commit fixes bug 1140882.
Merge pull request #5807 from Miciah/bug-1140882-oo-diagnostics-should-verify-that-PermitRootLogin-is-enabled-on-nodes-for-oo-admin-move

Merged by openshift-bot