Allow create volume group with block devices for lvm

Add new attribute, create_colume_group_type to allow
either create simple test volume based upon a file
(as existing support does),
or create volume group based upon block devices.

Change-Id: Ia81354f9fab9310c1b5e633d4ca05e434f9c2da6
Closes-Bug: #1321336
Merge "Allow create volume group with block devices for lvm"