Base scripts on the init scripts included with Debian GNU/Linux
then take code from the already existing ones, trying to merge
them into one.
+ NFS server service is just called 'nfs' in Redhat based system, and
  nfs-kernel-server on Debian GNU/Linux based.
+ Merge https://github.com/zfsonlinux/zfs/pull/2148 - Inform OpenRC that ZFS uses mtab.
+ Stop after umountfs
+ When stopping, don't check for LOCKDIR/zfs-mount - it won't be mounted,
  so the file won't exist making the script not run.
+ Add a configurable ZFS_INITRD_POST_MODPROBE_SLEEP used in the initrd to sleep after the modprobe.
+ The import function, do_import(), imports pools by name instead of '-a' [all].
  + Test all '/dev/disk/by-*' dirs for import.
+ Fallback on importing the pool using the cache file (if it exists) if the
  'by-id' didn't work.
+ Add exceptions to pool imports.