CLI: Adding warning message in case remove-brick commit executed

Change-Id: Ia2f1b2cd2687ca8e739e7a1e245e668a7424ffac
BUG: 1136702
Signed-off-by: Susant Palai <spalai@redhat.com>
Reviewed-on: http://review.gluster.org/8577
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>