Add volume_clear & volume_clear_size options for LVM

- Split out LVM configuration using LVM Driver
- Add volume_clear_size & volume_clear attributes/configuration
- Add tests for these values

Change-Id: I07376e3b3152e986ba1efeb9f1773fba1c4c436d
Closes-Bug: #1279756
Merge "Add volume_clear & volume_clear_size options for LVM"