scality: volume driver should use distributed lock manager

[Szymon Wróblewski]

In attempt to make Cinder HA A/A ready ScalityDriver should start using RemoteFSSnapDriverDistributed instead of RemoteFSSnapDriver, this will change locked snapshot operations to use distributed lock manager.
Moreover remotefs.locked_volume_id_operation decorator should be switched to coordination.synchronized:

@coordination.synchronized('{self.driver_prefix}-{volume.id}')
def method_using_volume(self, volume, snapshot):

@coordination.synchronized('{self.driver_prefix}-{snapshot.volume.id}')
def method_using_snapshot(self, snapshot):

Driver should also switch utils.synchronized(..., external=True) decorator to coordination.synchronized unless decorated method could be executed at multiple nodes at the same time.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/348034

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean McGinnis (<email address hidden>) on branch: master
Review: https://review.openstack.org/348034
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Sean McGinnis (sean-mcginnis)]

Unassigning due to no activity for > 6 months.