Ganet extstorage provider for local zfs volumes

INSTALLATION

  cd /usr/share/ganeti/extstorage/
  git clone https://github.com/ffzg/ganeti-extstorage-zfs zfs

  # enable new disk template

  gnt-cluster modify --enabled-disk-templates plain,drbd,ext \
	--ipolicy-disk-templates plain,drbd,ext

  # create log directory

  mkdir /var/log/ganeti/extstorage

  # try instance creation with something similar to

  gnt-instance add -t ext --disk=0:size=10G,provider=zfs \
	--disk=1:size=20G,provider=zfs \
	-n arh-hw --no-name-check --no-ip-check \
	-o debootstrap+default -B maxmem=512M zfs-ext-test