glusterd: remove-brick: prevent removal from a replicate volume.

Prevent the removal of brick(s) from a plain replicate volume and
display the error message at the CLI.

Change-Id: I8e182404564147329d8cd364b7c7931d19f14570
BUG: 961669
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Reviewed-on: http://review.gluster.org/4975
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>