Migrate cinderclient to OSC

Eventually OSC should implement volume commands in itself by
using python-openstacksdk,but now all of volume commands in
OSC are depending on cinderclient.

There is a bp shows that what volume commands are supported
now in OSC and what commands should implement in the future:
https://blueprints.launchpad.net/python-openstackclient/+spec/cinder-command-support
In this bp we can see there are about 33 commands are supported
and 23 commands are not supported in OSC now.But all of these
supported commands are depending on cinderclient.In this case,
if we continue to implement new volume commands using cinderclient,
it will be more and more difficult to migrate to OSC by SDK.But if
we stop,the progress of implementing volume commands will be delayed.
So,we should find a proper way to migrate cinderclient to OSC.

We can see in python-openstacksdk,there are only 9 volume commands
are supported,including:
volume create
volume delete
volume show
snapshot create
snapshot delete
snapshot show
volume type create
volume type delete
volume type show
It is much less than we need.We need more support in SDK for this work.

So,at first,we should add more support for volume commands in SDK.
Second,we should change those existent volume commands in OSC by using SDK.
Third,we can implement new volume commands in OSC by using SDK.