MB-9666: Persist the partition versions/failover log

With UPR there needs to be a way to determine where the
data came from. Hence the failover log of every partition
is persisted on disk.

This information will be used to determine whether a rollback
is needed or not in certain failure cases.

Change-Id: I950a102e18ab4223908c4b42f962d4a742840988
Reviewed-on: http://review.couchbase.org/30794
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: buildbot <build@couchbase.com>