Fix assert_stdout_add_file() Rhizome test function

Correct 'author' and 'secret' fieldnames to '.author' and
'.secret'
Improve Rhizome AddUpdateSameVersion test

If 'rhizome add file' command does not return status 1,
then cat the standard error (log) to the test log
fixup! fixup! Create authorless bundle from bundle secret
Create authored bundle from bundle secret

Improve the logic in rhizome_fill_manifest() to handle the case where
the secret and author are both supplied, by setting the BK field so the
secret can be recovered from the manifest later