opam-repo-dev now less useful

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

Now that OPAM is settling down, the mirage/opam-repo-dev remote is considerably 
less useful.  Its primary goal is to have the bleeding edge versions of all the 
repositories, but in practise this means that we just forget to cut releases, 
and users without this remote get errors.

Now, the easy alternative to having this remote is simply to 'opam pin 
git://foo/bar' to get a local development copy.  With this in mind, I think we 
should get rid of this remote, and instead use 
git://github.com/mirage/opam-repository to commit proper releases.

Thoughts? I'm particularly interested in Dave/Jon, as they may have hidden 
dependencies on opam-repo-dev that I don't know about.  But I suspect you've 
moved the Citrix stuff onto xen-org/opam-repo-dev...?

-anil