gluster: use replace brick cli xml output

glusterVolumeReplaceBrickStart, glusterVolumeReplaceBrickAbort,
glusterVolumeReplaceBrickPause and glusterVolumeReplaceBrickCommit use
gluster cli xml output than stdout parsing.

glusterVolumeReplaceBrickStart is not consumed by engine/RHS-C yet,
its OK to differ in compatibility issue now.

Change-Id: Iff789360953214c88ac8319f8cda48605c8cf3a7
Signed-off-by: Bala.FA <barumuga@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/13004
Reviewed-by: Timothy Asir <tjeyasin@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>