Document dmraid options

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Fix dmraid metadata collection and make it optional

The dmraid command writes metadata dumps into the current working
directory. This is normally /tmp meaning that the files are
created outside the archive.

Use runat to change directory to the appropriate path in the
archive before running the command and add an option to control
metadata collection.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Fix debugfs_path usage in kvm plugin

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>