Fix max filename size report by FAT statfs with long file names; Add missing...

Fix max filename size report by FAT statfs with long file names; Add missing logic to support fieldwidth and justification for %s format; Add extended help options.  Default help command just shows a short list of commands.  Verbose and single command help options

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5008 42af7a65-404d-4744-a932-0658087f49c3