opam: add version 0.8.1+dev pointing to master
opam-dev: add the cmdliner dependency
opam.0.8.1+dev: fix URL to "now"'s master

Opam is moving very fast so we prefer manual updates:
Now we point to
https://github.com/OCamlPro/opam/commit/29c0362c8506f83b7bee083cd05e5db1d807b2cb
(Tue, 18 Dec 2012 14:58:31 -0500)
eliom.3.0.3: add Grégoire's int64 patch
ocsigenserver.2.2.0: make dbm an optional dependency
ocsigenserver.2.2.0: depend on dbm OR sqlite
Merge branch 'fix_eliom_int64'
Merge branch 'make_dbm_optional'