Hooks/nfs-ganesha:Change the hook script to enable new function signature of add export.

Minor changes in the hook script to avoid some
possible confusion when volume set options are used.
Adding a few additional checks to ensure correct behaviour.

Edited a few config parameters that have changed in upstream
ganesha recently.

Change-Id: I85b842cbbd4b35b7f72f3beb60abf6532ddaa8c7
BUG: 1101416
Signed-off-by: Meghana M <mmadhusu@redhat.com>
Reviewed-on: http://review.gluster.org/7890
Reviewed-by: soumya k <skoduri@redhat.com>
Reviewed-by: Raghavendra Talur <rtalur@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>