LU-2863 tests: fix lfsck/OI_scrub test scripts issues

LU-2863 tests: fix lfsck/OI_scrub test scripts issues

1) sanity-scrub.sh checks Lustre version after Lustre initialization.

2) Re-calculate the expactation for lfsck/OI_scrub speed test:
   2.1) 1.1 * the theoretical value for speed upper limit.
   2.2) 0.9 * the theoretical value for speed lower limit.

3) Reformat the device before running sanity-scrub test_11.

4) Other cleanup.

Test-Parameters: testlist=sanity-scrub,sanity-lfsck

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Ib811fa24ac7581c341d596afbed064a4fc3e7357
Reviewed-on: http://review.whamcloud.com/5551
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>