ANN: cohttp-0.9.8

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

I've done a substantial rewrite of the internals of Cohttp to be much cleaner, 
which results in breaking changes to older code.  Thanks to the magic of OPAM 
[1], the public package constraints are all correct (with an upper bound of 
0.9.6 for older ones).  However, private forks will be broken until they either 
fix their interfaces or add an upper bound.

cohttp-0.9.8 (2013-05-24):
* Lwt interface change: Rewrite Lwt backends to share code, and remove 
duplicate function calls from Uri.
* Depend on `Uri` 1.3.8+ as it exposes the parameter query functions now 
removed from `Request`.
* Do not depend on Cstruct in core library, as only Mirage needs it.
* Remove `Cohttp_async.body` type alias and just use `string Pipe.Reader.t` for 
more explicit types.

[1] https://github.com/OCamlPro/opam-repository/pull/740