LU-419 increase default inode ratio for OST/MDT

LU-419 increase default inode ratio for OST/MDT

Increase the default inode ratio for large OSTs to avoid creating
far too many inodes, which can slow down e2fsck dramatically.

Decrease the default inode ratio for the MDT, since it never uses
the space that is allocated to it.  Also make this calculation take
the expected stripe EA into account, which wasn't done before.

Change-Id: Ic827d5f7a012fa07106e7e053abc0e646aba30ac
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/959
Tested-by: Hudson
Reviewed-by: Yu Jian <yujian@whamcloud.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>