MFC r246922 (pjd):

MFC r246922 (pjd):

- Add support for 'memsync' mode. This is the fastest replication mode that's
  why it will now be the default.
- Bump protocol version to 2 and add backward compatibility for version 1.
- Allow to specify hosts by kern.hostid as well (in addition to hostname and
  kern.hostuuid) in configuration file.

Sponsored by:	Panzura

git-svn-id: svn://svn.freebsd.org/base/stable/8@249237 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f