Add Support for Volume Groups via FlashCopy ManagementModel 2.0

This blueprint is to add support for Volume groups in IBM SVf cinder driver
created using a new group_type 'volume_group_enabled'.

For all groups created using the 'volume_group_enabled' group_type, user will be able to create/delete volume groups, add/remove volumes to group, create/delete group snapshots, and
trigger clone operations.