rpc/nfs: cleanup legacy code of general options

Removing the code which handles "general" options.
Since it is no longer possible to set general options which
apply for all volumes by default, this was redundant.

This cleanup of general options code also solves a bug wherein
with nfs.addr-namelookup on, nfs.rpc-auth-reject wouldn't work
on ip addresses

Change-Id: Iba066e32f9a0255287c322ef85ad1d04b325d739
BUG: 921072
Signed-off-by: Rajesh Amaravathi <rajesh@redhat.com>
Reviewed-on: http://review.gluster.org/4691
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>