Version 0.4.0

  * Add signature_manifest class.

  * Add repository_manifest::certificate.

  * When calculating repository canonical name, do not strip the prefix if
    the resulting name will be empty (e.g., /var/bpkg/1).

Version 0.3.0

  * Reimplement *-file manifest values as C++11 unions.

  * Add support for comments in the repository manifest email values.

Version 0.2.0

  * First public release.