LU-3529 lod: create striped directory

LU-3529 lod: create striped directory

1. Add "lfs setdirstripe -i -c" to create striped
directory.

2. client send create request to the master MDT, which
will allocate FIDs and create slaves. for all of slaves.

3. Client needs to revalidate slaves during intent getattr
and open request.

4. lmv_stripe_md will include attributes(size, nlink etc)
from all of stripe, which will be protected by UPDATE lock.
client needs to merge these attributes when update inode.

5. send create request to the MDT where the file is located,
which can help creating master stripe of striped directory.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I7ac560e39dcb415e310dc5e6ade531d76227ffae
Reviewed-on: http://review.whamcloud.com/7196
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>