LU-1415 tests: Adapt oos to the new grant and osd-zfs behavior

LU-1415 tests: Adapt oos to the new grant and osd-zfs behavior

This was originally developed by Johann Lombardi under ORI-151 and
ORI-398.  See http://review.whamcloud.com/1545 and
http://review.whamcloud.com/1665.

Change-Id: If778df1d672e2adb182cb801036aaef950d80af4
Whamcloud-bug-id: ORI-151
Whamcloud-bug-id: ORI-398
Signed-off-by: Li Wei <liwei@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/2978
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>
Reviewed-by: Niu Yawei <niu@whamcloud.com>