Implement Huawei SDSHypervisor driver

It uses socket and CLI to communicate with SDSHypervisor
to perform the following:
* Create/Delete Volume
* Extend Volume
* Create/Delete Snapshot
* Create Volume from Snapshot
* Delete Volume Snapshot
* Attach/Detach Volume
* Get Volume Stats
* Clone Volume

Certification test result for Huawei SDSHypervisor:
https://bugs.launchpad.net/cinder/+bug/1368064

Implements: blueprint huawei-sdshypervisor-driver
Change-Id: Ied72c5568875eae2387cf6271f31ddc5eebcc4bb
Merge "Implement Huawei SDSHypervisor driver"