fix up the Mirage interface so that the Server now works
fix up the Mirage interface so that the Server now works

It is still quite slow due to all the flushing and copying, but sufficient to minimally work

marklrh/ocaml-cohttp,fdopen/ocaml-cohttp,mor1/ocaml-cohttp,inhabitedtype/ocaml-cohttp,Drup/ocaml-cohttp,edwintorok/ocaml-cohttp,edwintorok/ocaml-cohttp,fdopen/ocaml-cohttp,inhabitedtype/ocaml-cohttp,Drup/ocaml-cohttp,dsheets/ocaml-cohttp,edwintorok/ocaml-cohttp,mor1/ocaml-cohttp,inhabitedtype/ocaml-cohttp,marklrh/ocaml-cohttp,marklrh/ocaml-cohttp,dsheets/ocaml-cohttp,Drup/ocaml-cohttp,dsheets/ocaml-cohttp,mor1/ocaml-cohttp,fdopen/ocaml-cohttp