heal: glfs-heal implementation

Thanks a lot to Niels for helping me to get build stuff right.

Change-Id: I634f24d90cd856ceab3cc0c6e9a91003f443403e
BUG: 1147462
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/6529
Reviewed-by: Krutika Dhananjay <kdhananj@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>