nfs-utils updates for Factory / 11.3

- nfsserver.init / sysconfig.nfs: allow NFSv3 service
to be disabled so only NFSv4 can be used. bnc#598671
- nfs-v2-disable.patch: mountd support for above
- nfs.init: unmount bind mounts with '-l' to ensure they
really unmount. bnc#598681

- mkinitrd-boot.sh: allow other mkinitrd-setup
scripts to request the inclusion of nfs support
by setting need_nfs to 1. (bnc#572207)

- sysconfig.nfs, nfsserver.init, start-start: handle
STATD_OPTIONS so that sysadmin can easily set options
like port number. (bnc#595379)