webadmin : gluster volume rebalance status and start time formatting

Earlier the start and status time of volume rebalance was not shown

in a correct format.Now,it is displayed in the appropriate format.

Change-Id: I8897a9aa141120fe5e9011167e7a1d14a24c4852
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1011878
Signed-off-by: Anmol Babu <anbabu@redhat.com>