Fix issue with sessions detail command
Fix issue with sessions detail command

Do not reference the backstore, access the plugin field off the so
directly. This is a regression introduced with the backstore removal
changes a while back.

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

cloud4life/targetcli-fb,agrover/targetcli-fb,cvubrugier/targetcli-fb