nfs: Add rpcbind

rpcbind is needed by the NFS client. rpcbind was removed during a
cleanup process and is now re-added.

rhbz#902677

Change-Id: Icceb609aa590b1ff77d490fd2780ee4bd8fb5b2c
Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>