High: nfsserver: Improve support for v3 file lock recovery

The nfs-lock daemon may look in /var/lib/nfs/sm or
/var/lib/nfs/statd/sm depending on the version. This patch detects
if the statd folder should be used for lock failover.
High: nfsserver: Maintain SELinux permissions on failover for nfs v3 lock state
High: nfsserver: Enable file locking daemon when systemd is being used
Merge pull request #230 from davidvossel/nfs_v3_failover2

nfs v3 failover improvements