geo-rep: Handle RMDIR recursively

If RMDIR is recorded in brick changelog which is due to
self heal traffic then it will not have UNLINK entries for
child files. Geo-rep hangs with ENOTEMPTY error on slave.

Now geo-rep recursively deletes the dir if it gets ENOTEMPTY.

BUG: 1138952
Change-Id: Ie79db90c52103b39fa795bb8a096b363d450b427
Signed-off-by: Aravinda VK <avishwan@redhat.com>
Reviewed-on: http://review.gluster.org/8477
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>
Tested-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/8643
Reviewed-by: Vijay Bellur <vbellur@redhat.com>