gluster: Corrected event log msg for add brick

Corrected event logging during add bricks to a volume.
Earlier it was nto showing the details of the bricks being added.

Now details of individual bricks being added are displayed and finally a
summary of total added bricks is displayed in the event audit logs.

Change-Id: I05054de122a916d25c14adc05efdc484a0c133f1
Bug-Url: https://bugzilla.redhat.com/957003
Signed-off-by: Shubhendu Tripathi <shtripat@redhat.com>