LU-653 i_version shouldn't be used for VBR

LU-653 i_version shouldn't be used for VBR

RHEL6 plus EXT4 combination cause i_version is to be used to store
Lustre versions instead of i_fs_version. Meanwhile this field is used
by ext4 internally and may be changed breaking Lustre recovery.

Patch makes only i_fs_version to be used for versions.

Change-Id: Idf7cd257aa2d288abce2a7c18c4d8b139bc9c5c6
Signed-off-by: Mikhail Pershin <tappro@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/1342
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Hudson
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Tested-by: Yu Jian <yujian@whamcloud.com>