RFC: make the experimental NFS subsystem the default one

[Rick Macklem]

> 
> - Has the experimental code been stress-tested? If so, how? I've heard
> of people doing silly things like testing with filesystem benchmark
> utilities -- which pass/work fine, but the instant someone tries
> using something like rsnapshot (like we do), the thing falls apart.
> 
Just fyi, Peter Holms (pho@) has volunteered to do some stress testing,
which is now in progress.

Thanks go to him for doing this, rick