LU-1415 tests: Add ZFS support to replay_barrier()

LU-1415 tests: Add ZFS support to replay_barrier()

This patch makes sure that ZFS pool states changed by replay_barrier()
calls are restored upon subsequent failovers.

This was originally developed by Mikhail Pershin under ORI-156.  See
http://review.whamcloud.com/1490.

Change-Id: Ie8d26bc8a6d6103be3c504e0af80e8499096df58
Whamcloud-bug-id: ORI-156
Signed-off-by: Li Wei <liwei@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/2981
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Mike Pershin <tappro@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>