This includes:
adding --metadata= option to choose metadata format
adding metadata= word to config file.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
This allows for larger device number if glibc supports
it (requires 2.3.3).
Also fail before creating larger device number if glibc
support isn't present.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
