cluster/dht: Don't do extra unref in dht-migration checks

Problem:
syncop_open used to perform a ref in syncop_open_cbk so the extra
unref was needed but now syncop_open_cbk does not take a ref so no
need to do extra unref.

Fix:
remove the extra fd_unref and let dht_local_wipe do the final unref.

Change-Id: Ibe8f9a678d456a0c7bff175306068b5cd297ecc4
BUG: 961615
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Signed-off-by: Vijay Bellur <vbellur@redhat.com>
Reviewed-on: http://review.gluster.org/8029
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: Joe Julian <joe@julianfamily.org>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
doc: Fix peer probe deficiencies

Added the command to probe the first server to assign it a hostname

Change-Id: I67f35553df74718f23cd8453dc7854a44c61be11
BUG: 1095596
Reviewed-on: http://review.gluster.org/7854
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>