initial: Initial working version of gvolinfojson

A utility to convert xml output of gluster volume info to json.

Run gluster volume info command and pipe its output to gvolinfojson.
sudo gluster volume info --xml | gvolinfojson

If you need to print pretty JSON output, then
sudo gluster volume info --xml | gvolinfojson --pretty

Signed-off-by: Aravinda VK <mail@aravindavk.in>