Move Eliom_service.external_{,post_}service to Eliom_service.{Http,App,Ocaml,Unsafe}
Update the doc against the previous change
Add an optional ?rt parameter to Eliom_service.Http.external_service (in case of an external ocaml service)
Don't allow external app services
Yet another update against the previous change
Merge pull request #57 from ocsigen/external_service

Move Eliom_service.external_{,post_}service to Eliom_service.{Http,Ocaml,Unsafe}