signature.py: enforce sane gpg options
- Add
--batchsincegpgis not run manually. - Add
--no-armorto ensure that a.sigfile is created instead of.ascin casegpg.confsets thearmoroption. - Add
--no-include-key-blockto skip including the public key in the signature and force the user who verifies the signature to acquire the public key from elsewhere.
Fixes #15 (closed).