cli: Xml output for geo-replication config command

This patch adds xml output for geo-replication config
command.
sample:
---------------------------------------------------------------------
<cliOutput>
  <opRet>0</opRet>
  <opErrno>0</opErrno>
  <opErrstr/>
  <geoRep>
    <config>
      <parameter1_name>value</parameter1_name>
      <parameter2_name>value</parameter2_name>
      ...
      ...
      ...
    </config>
  </geoRep>
</cliOutput>
---------------------------------------------------------------------

Change-Id: Iac0451983ae5d0e65b95604eb1c29b968e1ee22f
BUG: 1121518
Signed-off-by: ndarshan <dnarayan@redhat.com>
Reviewed-on: http://review.gluster.org/8270
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaushal M <kaushal@redhat.com>