Mox -> Mock for test_block_device.py

Change-Id: I9a8aec5464054da95099a411c17f58f656033eab
Add support to PureISCSIDriver for Consistency Groups

This change adds implementations for the required driver methods for
Consistency Groups to be supported with the PureISCSIDriver. There is a
nice direct mapping between Consistency Groups and Purity Protection
Groups which makes the implementation pretty straightforward.

Implements: blueprint pure-iscsi-consistency-group
Change-Id: I8b97947d4788a7a7ba2dfa1d2b07645eafba76ec
Remove check on db_exc.DBError

After using oslo.db >= 0.4.0 we will never get DBError Exception

Change-Id: I94d6a155df1d71658e7271ab4d55122906216a87
Merge "Remove check on db_exc.DBError"
Merge "Mox -> Mock for test_block_device.py"
Merge "Add support to PureISCSIDriver for Consistency Groups"