Update some packages using oasis2opam

Before I do some more (I need to test the tool and this increases the metadata in OPAM packages along the way!), tell me what you think about using opam-devel@lists.ocaml.org when no email is found in the _oasis file.  My motivation is that there are many more people on the list than at contact@ocamlpro.com which may speed up the resolution of problems (and also report problems which may potentially affect a set of packages to a wider audience).