gluster : In the task tab, size of rebalanced files is shown with units

The size of files rebalanced was shown in bytes.

Now,the size is shown in larger units.

Change-Id: Iea6c90a098bfddfb616bc2b8ce58c9d0bb567f66
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1020883
Signed-off-by: Anmol Babu <anbabu@redhat.com>