[OCaml] Various corrections in the comments
[OCaml] The Makefile now compile the project in a library

- Library `.cma` to be added in your projects
- `make example` to compile an example of usage of the library
- `example.ml` contains an example of usage of the library
- New module `ApiDump` to display some API values for testing and debug purpose
[OCaml] API user's conversations methods
[OCaml] ApiUser: get tokens, get friends
[OCaml] API tool to generate the list of get parameters for pagination lists

(** Methods that return an API List take two optional parameters.             *)
(** This function take both + a list of other parameters and return final list*)
val pager :
  int option (* index *) -> int option (* limit *)
  -> (string * string option) list -> (string * string) list
[OCaml] Be friend with another user
[OCaml] Cancel friendship with another user
[OCaml] Cancel friendship between two users (only for administrators)