After client pod is stopped we need to wait for a while for kubelet to
unmount and clean up the client pod before we can destroy the server pod.
Killing e.g. iSCSI server too early may result in stale attached device
that cannot be removed.
- create 120MB volume instead of 1MB for volume_io tests
- rebase to Fedora 26
- added compatibility with ext4 and older ceph clients
- unify CephFS and Ceph RBD images.
