what's_new: move link to comprehensive list of changes
releases: import http://caml.inria.fr/ocaml/release.en.html

Partly addresses #39.
move svn info from install to new file

As discussed in #75, this information is about releases, not an
installation instruction.
import http://caml.inria.fr/ocaml/release-prev.en.html

Partly addresses #39.
releases: fix links to Inria