In order to sign packages, you have to create a signing key pair and
place it in /opt/openrobots/etc/gnupg.

This can be done by running the following interactive command:
  /usr/bin/gpg --homedir=/opt/openrobots/etc/gnupg --gen-key

To export the public key into a file, use the following:
  /usr/bin/gpg --homedir=/opt/openrobots/etc/gnupg --output public.key -a --export

To change the default directory, set GPG_HOMEDIR in robotpkg.conf
