glusterd: Moved the volume entry table to a separate file.

Change-Id: I893f41bd505fc0e02aec1e71f7a6209759b24a89
BUG: 903478
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/4517
Tested-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Kaushal M <kaushal@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>