The new version of ocplib-resto :
- uses jbuilder ;
- is functorized over `Json_encoding` rather than `Json_repr` ;
- handles query parameters ;
- handles HTTP methods (GET, POST, DELETE, PUT, PATCH) ;
- replaces `custom_service` by a more generic trailer argument ;
- replaces generic answer `(code, body)` by a more ad-hoc sum type
(allowing distinct encoding for success and error) ;
- includes a minimal HTTP-server based on Cohttp
(includings CORS and media type negotiation).
- adds a function `Directory.transparent_lookup` to lookup/call
a service handler without serializing the various parameters
(path, query, request body).
As a first consequences in Tezos, this patch allows binary
communication between the client and the node.
This patch tries to be minimal inside the tezos source code and
therefore it introduces a minimal compatibility layer in
`RPC.ml`. This code should be removed as soon as possible.
