Add an option (--detached) to sbsign, which creates a detached
signature, rather than embedding it in the PE/COFF signature table.
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Update the usage output of sbsign and sbverify so that it can be better
parsed by help2man. Also, add --version and --help.
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>