re-work.

Following are the cli commands that are new/re-worked:
======================================================

volume quota <VOLNAME> {enable|disable|list [<path> ...]|remove <path>| default-soft-limit <percent>} |
volume quota <VOLNAME> {limit-usage <path> <size> [<percent>]} |
volume quota <VOLNAME> {alert-time|soft-timeout|hard-timeout} {<time>}
volume status [all | <VOLNAME> [nfs|shd|<BRICK>|quotad]] [detail|clients|mem|inode|fd|callpool]
volume statedump <VOLNAME> [nfs|quotad] [all|mem|iobuf|callpool|priv|fd|inode|history]

glusterd changes:
=================
* Quota limits are now set as extended attributes by glusterd from
  the aux mount created by the cli.
* The gfids of the directories on which quota limits are set
  for a given volume are stored in
  /var/lib/glusterd/vols/<volname>/quota.conf file in binary format,
  and whose cksum and version is stored in
  /var/lib/glusterd/vols/<volname>/quota.cksum.

Original-author: Krutika Dhananjay <kdhananj@redhat.com>
Original-author: Krishnan Parthasarathi <kparthas@redhat.com>

BUG: 969461
Change-Id: If32bba36c67f9c2a30417af9c6389045b2b7c13b
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-on: http://review.gluster.org/6003
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>