[sheepdog] [ANNOUNCE, CAUTION] sheepdog stable release v0.8.3_rc0

[Hitoshi Mitake]

Hi sheepdog users and developers,

I released v0.8.3_rc0 of stable branch. You can download a source
archive from these URLs:
tar.gz: https://github.com/sheepdog/sheepdog/archive/v0.8.3_rc0.tar.gz
zip: https://github.com/sheepdog/sheepdog/archive/v0.8.3_rc0.zip

This update contains important bugfixes, especially related to
zookeeper driver. In addition, enhancements of log messages are
backported.

I have to emphasis on the point that updating from v0.8.x (x < 3) to
v0.8.3_rc0 requires "-u" option, because it contains updating store
format. Sorry for inconvenience but the format update is a necessary
change for clusters which store many objects.

If no one disagrees about this release candidate in 2 days, it will be
v0.8.3 officially.

Below is a summary of commits:

Meng An (1):
      sheep: remove last slash for new->path in md_add_disk()

Ruoyu (8):
      sheep/zookeeper: ensure zookeeper is connected
      zk_control: add list and purge queue nodes
      zookeeper: fix zk_event structure not initialized
      sheep/ops: fix incorrect error log on remove_epoch
      sheep/request: straightforward error message in sheep_exec_req
      lib/event: fix and unify error message
      sheep/cluster: remove ephemeral node when zookeeper master leaves
      sheep/request: fix fd leak

Thanks,
Hitoshi