Add support for our format version

We had previously started on a relatively simple notion of an
interoperability version which wasn't quite right.  This fleshes out
support for a more functional format version.   The super blocks have a
single version that defines behaviour of the running system.   The code
supports a range of versions and we add some initial interfaces for
updating the version while the system is offline.   All of this together
should let us safely change the underlying format over time.

Signed-off-by: Zach Brown <zab@versity.com>

utils/src/cmd.c

@@ -8,6 +8,7 @@
 
 #include "cmd.h"
 #include "util.h"
+#include "format.h"
 
 static struct argp_command {
 	char *name;
@@ -69,6 +70,9 @@ static void usage(void)
 	fprintf(stderr, "Selected fs defaults to current working directory.\n");
 	fprintf(stderr, "See <command> --help for more details.\n");
 
+	fprintf(stderr, "\nSupported format version: %u-%u\n",
+			SCOUTFS_FORMAT_VERSION_MIN, SCOUTFS_FORMAT_VERSION_MAX);
+
 	fprintf(stderr, "\nCore admin:\n");
 	print_cmds_for_group(GROUP_CORE);
 	fprintf(stderr, "\nAdditional Information:\n");