cli: Xml output for geo-replication status command.

This patch adds xml output for geo-replication status
and status detail command.
sample:
--------------------------------------------------------------
  <geoRep>
    <volume>
      <name>master</name>
      <sessions>
        <session>
        <session_slave>:2a301d66-b9d2-44b4-b827-d680d67123eb:ssh://XXXXXXXXXX::slave</session_slave>
          <pair>
            <master_node>localhost.localdomain</master_node>
            <master_node_uuid>2a301d66-b9d2-44b4-b827-d680d67123eb</master_node_uuid>
            <master_brick>/root/master_b1</master_brick>
            <slave>ssh://XXXXXXXXXXX::slave</slave>
            <status>faulty</status>
            <checkpoint_status>N/A</checkpoint_status>
            <crawl_status>N/A</crawl_status>
          </pair>
        </session>
      </sessions>
    </volume>
  </geoRep>
-------------------------------------------------------------

Change-Id: Ia19dbe751c3ab1ec7cb8923cdd6c8b99c374072f
BUG: 1121518
Signed-off-by: ndarshan <dnarayan@redhat.com>
Reviewed-on: http://review.gluster.org/8089
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaushal M <kaushal@redhat.com>