LU-2587 quota: bump version after migration

LU-2587 quota: bump version after migration

The global index version should be bumped to 2 if migration
happened, otherwise, the global index copy version on slave will
be same as the global index's (both equal to 1 after creation),
and the migrated limits will fail to be reintegrated.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: I2d596a33e2eb4495dfbb7bd63d37199297a9b214
Reviewed-on: http://review.whamcloud.com/4969
Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>
Tested-by: Hudson
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>