cluster/afr: Add afr-v1 xattr compatibility

All the special cases v1 handles and also
self-accusing pending changelog from v1 pre-op also is handled
in this patch.

Change-Id: Ie10f71633fb20276f01ecafbd728f20483e7029c
BUG: 1128721
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/8536
Reviewed-by: Ravishankar N <ravishankar@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>