Currently there is no easy way for user to know the available
space in each logical volume group. This commit adds a new
column for each logical volume group to show the size of
available space.
Change-Id: Iba4c22587ba962596cf50e75cbc9cdd548301acc
Closes-Bug: 1804711
Depends-On: https://review.openstack.org/#/c/619656
Signed-off-by: Wei Zhou <wei.zhou@windriver.com>