New HP LeftHand array iSCSI driver

New HP LeftHand array iSCSI driver

This driver is intended to replace the current OpenStack Block
Storage HP LeftHand (LH) StoreVirtual iSCSI Driver,
(cinder.volume.drivers.san.HpSanISCSIDriver), by moving the
existing SSH interface into the new driver to maintain backwards
compatibility, and add the new LH REST interface for new driver
features.

We have the driver broken into 3 files:
hp_lefthand_iscis.py (common interface)
hp_lefthand_cliq_proxy.py (old SSH interface)
hp_lefthand_rest_proxy.py (new REST interface)

The reason we are doing this is because the SSH interface on LH
array has connections and performance limitations. These problems
will be resolved by moving to the new LH OS REST interface. Also,
new LeftHand array capabilities will only be supported in the
REST(hplefthandclient) interface.

To support new driver capabilities (create cloned volume), the
python REST client (hplefthandclient) is required and can be
downloaded from the pypi repository:
  http://pypi.python.org/pypi/hplefthandclient.
This REST client requires LeftHand firmware version 11.5 or
greater.

The SSH interface will be phased out over time.

Driver cert test results;
Related-Bug: 1276809

Closes-Bug: 1277339

DocImpact: Document new driver configuration.

Implements blueprint lefthand-cinder-driver

Change-Id: Id557cab69022c3f7851be14cd82bdab0e4157e55