LU-6586 mgs: deactive MDT permanently

LU-6586 mgs: deactive MDT permanently

Deactivate/activate MDT in the config log, so
the user can permanently deactivate one MDT.

Add active proc entry for MDC, and mark MDC to
be inactive once the MDC is deactivated.

Add conf-sanity.sh 50i to verify activate
and deactivate MDT.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ia8d18f48f12fc180c32da777bde0902a774ddf93
Reviewed-on: http://review.whamcloud.com/14747
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>