CLI: Show warning on remove-brick commit
Signed-off-by: Susant Palai <spalai@redhat.com>

Change-Id: I48a4168f81bd272216549c76b0bc1b23e34894d6
BUG: 1136702
Reviewed-on: http://review.gluster.org/8664
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: N Balachandran <nbalacha@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>