glusterd : initiating gsyncd restart during add-brick

During add-brick, when a new brick is added in one of the
nodes that was already a part of the existing volume, and
gsyncd was already running on that node, then all gsyncd
processes running on that node, for that particular master
and any slave sessions will be restarted

If a new brick is added in a new node, then after adding the
brick, the user has to perform the following steps:

1. gluster system:: execute gsec_create
2. gluster volume geo-replication <master-vol> <slave-vol> create push-pem force
3. gluster volume geo-replication <master-vol> <slave-vol> start force

Change-Id: I4b9633e176c80e4a7cf33f42ebfa47ab8fc283f1
BUG: 989532
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/5416
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>