Fix bug introduced by f5677ab
Fix bug introduced by f5677ab

Commit f5677ab added the _VerifyOob functionality, but there are two
issues with this function:

- a real bug, as objects.Node doesn't have a 'master' attribute
- a design bug, as we need to verify the OOB programs not only on
  current masters, but on all nodes that can become masters via the
  auto-promote functionality; otherwise, an automated cluster operation
  could cause the cluster to become inconsistent (error in verify)

The Node.master bug didn't appear in QA because it is triggered only
with non-master-candidate nodes, and our QA doesn't test this
combination (and neither other node flags combination).

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>

grnet/snf-ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/snf-ganeti,mbakke/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,bitemyapp/ganeti,bitemyapp/ganeti,yiannist/ganeti,ganeti/ganeti,apyrgio/ganeti,ganeti/ganeti,dimara/ganeti,leshchevds/ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,yiannist/ganeti,ganeti/ganeti,grnet/snf-ganeti,onponomarev/ganeti,leshchevds/ganeti,dimara/ganeti,andir/ganeti,mbakke/ganeti,apyrgio/ganeti,leshchevds/ganeti,andir/ganeti