Verify subkey revocation signatures according to: RFC4880 Errata ID: 3298

http://www.rfc-editor.org/errata_search.php?rfc=4880&eid=3298
This is now compliant to GPG (and other implementations).
See: http://lists.gnupg.org/pipermail/gnupg-devel/2014-February/028267.html
Activated skipped unit tests