Display sizes for backstores that support it
Display sizes for backstores that support it

Use bytes_to_human to print their size in the summary, for
storageobjects that support a size attribute.

Signed-off-by: Andy Grover <agrover@redhat.com>

Merged by Jerome Martin <tramjoe.merin@gmail.com>
Conflicts:
	targetcli/ui_backstore.py

Datera/targetcli,Datera/targetcli