webadmin: column sorting support for Storage sub-tabs

Enabled column sorting for sub-tabs under Storage main-tab.

Note:
column sorting isn't supported for tree-based sub-tabs,
hence, sorting for VMs/Templates sub-tabs is not applicable.

Change-Id: I210701c4498fc7a057fd1ed7154e0e9bcb572248
Signed-off-by: Daniel Erez <derez@redhat.com>