LU-1445 ofd: Add fid support on OFD

LU-1445 ofd: Add fid support on OFD

1. Init fid server related structure in OFD, which will
become a sequence metaserver, i.e. MDT will request sequence
from OST(OFD), OFD will request super sequence from MDT0

2. OST FID sequence width will be 4 billion, which is different
with MDS FID.

Change-Id: If861cf5814ea77ce72464525a8de71ac182d742c
Signed-off-by: Wang Di <di.wang@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/4326
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>