Move clear_volume back to it's own method

This just moves clear_volume back to it's own method
and also only calls volutils.clear if we actually
need to perform the clear operation.

Also takes out the hard-coded multiplier of 1024 and
uses units.GiB.  Maybe this should be a separate patch,
I'll spin another if there are objections.

Change-Id: I56f6690fbadc0d44eba48f49d29386d5b9dca195
Implement retype in SolidFire driver

This just adds the ability to modify the
type of an existing SolidFire volume to
another type suppported on the same backend.

Main use case for this is changing QoS settings
for a volume on-demand.

Also updates the internal attributes to store the
deltas between the old-type and new-type.

Change-Id: I65a4c34cbec17d0f3987c1d964e6ad1bafea3601
Implements: blueprint retype-support-for-solidfire-driver
Fixes cinder failed to create/restore a backup with NFS driver

The action cinder backup-create fails when trying to backup a newly
created volume when using cinder.volume.drivers.nfs.NfsDriver. This
patch removes not implemented stubs for backup_volume and
restore_volume. The inherited methods in cinder/volume/driver.py
succeed in creating a backup and in restoring it. After manual
testing of this change backups/restores succeed without the not
implemented stubs. This change also adds the not implemented
stubs to the glusterfs driver until a fix is submitted.

Closes-Bug: #1247743

Change-Id: I5478d00442ce855c91a7f04c5ba2b40733d44902
Add method for unit tests to set logging level

Implements: blueprint cinder-testcase-set-loglevel
Change-Id: Id4bb7023659eda593cc5ac451aa580f68a1a6b9d
Merge "Implement retype in SolidFire driver"
Merge "Fixes cinder failed to create/restore a backup with NFS driver"
Merge "Move clear_volume back to it's own method"
Merge "Add method for unit tests to set logging level"