cli: gluster volume heal commands are more elaborative

1. "gluster volume heal volume-name"
output :Launching heal operation to perform index self heal on volume volume-name has been successful

2. "gluster volume heal volume-name full"
Output :Launching heal operation to perform full self heal on volume volume-name has been successful

3. "gluster volume heal volume-name info"
Output :Gathering list of entries to be healed on volume volume-name has been successful 

4. "gluster volume heal volume-name info healed"
Output :Gathering list of healed entries on volume volume-name has been successful 

5. "gluster volume heal volume-name info split-brain"
Output :Gathering list of split brain entries on volume volume-name has been successful 

6. "gluster volume heal volume-name info heal-failed"    
Output :Gathering list of heal failed entries on volume volume-name has been successful 

Change-Id: I74c90e8129d23d513ddb7879358a9d21c94a5c0d
BUG: 978936
Signed-off-by: Venkatesh Somyajulu <vsomyaju@redhat.com>
Reviewed-on: http://review.gluster.org/5286
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>