gluster: Shown command and server name in evt log

Corrected the event log message shown in case a host goes
non-operational due to some issues. Earlier the message used to be shown
in the form "Gluster command [<UNKNOWN>] failed on server <UNKNOWN>."

Change-Id: I5857284b76a56f8b6b3cb8431a6997443939bb8c
Bug-Url: https://bugzilla.redhat.com/973624
Signed-off-by: Shubhendu Tripathi <shtripat@redhat.com>