webadmin: Storage main-tab - support column sorting

Applied 'makeSortable' method to columns that are
supported by search mechanism.

ToDo: implement custom comparators for columns that
are not supported by search (e.g. 'Total Space').

Change-Id: I689c86d2fb0e0b9070434d17aa4977a64d660cc1
Signed-off-by: Daniel Erez <derez@redhat.com>