OPAM dev repo updated for 108.08.00-pre0

[Anil Madhavapeddy]

I've pushed the package descriptions for 108.08.00-pre0 to this repo:
https://github.com/avsm/opam-core-pre0

...if anyone else also wants to test it. You can do so via:

$ opam remote -add coredev git://github.com/avsm/opam-core-pre0
$ opam update
$ opam upgrade

There's also a clone.sh script in there which clones an existing
version and rewrites the URLs to the new version, to make it easier
to generate the boilerplate for future versions.

-anil