Include option '--human-readable' to 'image show' command.
This option displays image size in human readable format
(such as K, M, G, T,..)
Related Commit: I0ef74c2ec978483fe49156c88acf5c369a8fa5c2
Closes-Bug: #1640086
Change-Id: I28cd5702925d51303d0607ed8dccf12c56434682