glusterd/snapshot: Update fstype for local bricks only

While creating snapshot, update fstype for local bricks only
and not for bricks hosted on other nodes

Also returning ret as 0, in case no cleanup is required in
post-validation, so that a post-validation failure is not
logged, every time a pre-validation failure happens.

Change-Id: I6364e33cfd9528e0a988ee48f3443239ee884336
BUG: 1111060
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/8272
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Tested-by: Krishnan Parthasarathi <kparthas@redhat.com>